this patch treats pkg and src deps as equals, so level decides winner

Instead fetching and resolving src deps (which could depend on pkg deps)
and then pkg deps this patch combines the two into a single set of
iterations by level. The only difference between src and pkg deps in this
new install_deps is how their deps list is found -- from the config or
lock file for src deps and from the neighbors of the vertex for pkg.

fix leaking hex_registry table

properly update locks for deps and ignore skip messages for locks

fix leaking ets tables when compilation failed

Modify parse_git_url to be more generic

Ferd add mixed deps tests

fix leaking ets tables caused by digraphs

Just rework the error message.

On a single app's dep list, the first noted wins if there's a duplicate
between packages and sources, rather than favoring source there anyway.

Requires a rework of other test suites using the same dep-handling
mechanism.

Tree provider

install package deps in same level/profile order as src deps

Dialyzering

Fix some unknown functions/types dialyzer warnings

don't run rebar2 get-deps in travis

fix dialyzer warnings, except 'no local return' warnings

Changes parse_git url function to use Using RFC3986 standard to validate
git uri instead of matching strings in function head. Also accepts scp
style syntax for parsing.

Detect missing EPMD, error, fallback and advise.

add tree option to deps command that prints pkg deps tree