make v prefix in git tag version optional

Revert "Improved git versioning"

fix #790

add 'bare compile' provider, for starters for use by mix

Improved git versioning

Fix parsing of version #'s of dependencies

Version #'s with patch info like "1.1.1-x" would cause an error. Now
tokenize the version string with "." AND "-".

In the scenario we that we have selected a commit
that is between two tags, we should base the
version on the most recent tag we can see in the
revision history, but we should not treat this as
the tag version.

`git describe --tags` finds the most recent tag
visible in the revision history from the current
HEAD. Return this as the version string and
undefined as the tag to trigger ref counting.

In the scenario that someone had cloned an entire
repository and then checked out an older version
tag, the semantic versioning would detect the
newest tag, not the checked out tag. Look for
the HEAD string prior to tag: to indicate the
currently selected tag.

Not all repositories use a v-prefix for version
tags. All tags should be considered valid
versions.

update travis for s3

Fix typo in plugins command help

Add plt_include_all_deps dialyzer option

`reduce_path/1` -> `canonical_path/1`
`relative_path/2` -> `path_from_ancestor/2`

Terms is already a list

this test almost certainly only fails under very limited circumstances
limiting it's utility. it is known to fail with some versions of rebar3
when this test is run via `rebar3 ct --cover`

replace noinput with noshell so providers that ask for input work

add tests

parse versions in deps tree output and support checkouts

use full path of apps for priv files included in escript

Fixes compiling yaws, which has an .app.src.script file

cover compile beams compiled for ct/eunit seperately from beams compi…

fixes #788

check checksum of rebar3 download in local_upgrade provider

add 'local install' and 'local upgrade'