Compiler source paths in output are now relative

partially addresses #1184

add support for passing a sys_config to common test

Expand os ENV proxy support to bootstrap script

Support ENV config for proxy values

- The configured stuff in rebar3 takes precedence over the ENV
- The env is then chosen

Write rebar3.crashdump on errors

This uses the env variable as a global store for variables. It's not the
cleanest thing, but it sounded nicer than pdicts.

This reworks the version and hash printing in the lockfile to minimize
diff changes:

- the version is on its own line so that the locks are mostly the same
  aside from the last line
- the hashes are each printed on one line with the package name for
  simpler diffing too.

This required moving the reporting functions to rebar_base_compiler but
since this was already done for error_tuple, this seems to make sense.

Paths are also reformatted for warnings in erlc files.

Fix compile error case when cover compilation

This will allow us to eventually change the default type without it
looking ridiculous.

Bugfix for upgrading deps of umbrella apps

Fix minor typo in README

The previous iteration of the patch worked somewhat by accident. After
digging in and figuring out why the two dep sources are the way they
are, the patch is now properly working with a well-documented
explanatiion inline.

Handle control sequences in formatted errors

Formatted errors can accidentally contain substrings which are control
sequences for io:format/2. This is a naive attempt to handle such cases.

One example is running xref on the following module
(assuming module m does not exist)

```
-module(handle_error).

-export([f/0]).

f() -> m:'bobby~stables'().
```

```
$ rebar3 xref
===> Verifying dependencies...
===> Compiling myapp
===> Running cross reference analysis...
escript: exception error: bad argument
  in function  io:format/3
     called as io:format(<0.23.0>,
                         "\e[0;31m===> \e[1mWarning: handle_error:f/0 is unused export (Xref)\nWarning: handle_error:f/0 calls undefined function m:bobby~stables/0 (Xref)\n\n\e[0m\e[0m",
                         [])
  in call from rebar3:handle_error/1 (/Users/gomoripeti/git/rebar3/_build/default/lib/rebar/src/rebar3.erl, line 279)
```

When the operation for an unlock takes place in the config of a umbrella
application, the `unlock' provider does not see the dependency in the
`deps' value of the config (since it only includes the deps at the root
of the project) and ignores these.

Don't die when source deps with [raw] are used

Debug log update

This adds support for their format both on the first read and when
looking for modifications to dependencies.

- also making sure unlocking works fine

Tests have broken as locks were expanded and auto-filled newer versions
of lockfiles. This fixes them back.

- the internal representation for package locks moves from `{Name, {pkg,
  PkgName, Vsn}, Lvl}` to `{Name, {pkg, PkgName, Vsn, Hash}, Lvl}`
- the internal representation for packages moves from `{pkg, PkgName,
  Vsn}` to `{pkg, PkgName, Vsn, Hash}`
- the hash can be `undefined`, meaning no check will be done
- no checking is done yet.

adjust `data_dir_correct` test in ct suite

don't bother checking the profile in the path to the data dir

filter available package versions individually by buildtools

deploy escript to travis releases instead of s3

Fix path command to consider {deps_dir, "deps"} in rebar.config

#1185 fix windows git working directory

fix issue #1185 git working directory issues due to command line options in Windows

don't needlessly update the code path twice if no hooks to run

don't generated coverage for `extra_src_dirs`