Confirm the supplied ref is valid in GitRepo#resolve[_full].

The '^{commit}' suffix causes rev-parse to check the ref resolves to
a commit, and not just that it's a valid-looking ref. Without it, any
40-character SHA will be resolved to itself, and appear to exist in
the repo.
Make the 'multiple installations' log message a bit clearer.

Answering 'y' at this prompt says "yes, attempt to meet the dep", not
"yes, consider it met".

That is, the choice is between attempting to continue as normal and
bailing out immediately, not whether or not to bypass this dep's
normal logic.
Add basic zypper and openSUSE support
Add openSUSE 13.2
fix typo
use /etc/os-release instead. Cannot test any of that locally. Sorry for the try and error
Fixed openSUSE recognition
Alphabetise the manager keys.
No need for so many choices here.

All we need is the ones we supply below, plus a few others for good
luck.
Comment & whitespace.
Test FedoraSystemProfile with verion 19.

It has an umlaut, to test non-ASCII support. At least I think that's
the reason I changed this.
Sometimes gcc is installed separately to the other OS X tools.

closes gh-312
Merge branch 'robwarm/opensuse'
Oops, 3a2cdd7 broke the specs on ruby-1.9.
ShellHelpers cmd_dir should not return directories that match cmd_name
Merge remote-tracking branch 'cheister/master'
Log correctly before tagging a new release.
Fix descendant checking in the release deps.

It was checking against HEAD ('stable' at that time) and not 'master'.
v0.18.2 - Opensuse, a #cmd_dir fix, OS X build tools.

* Basic opensuse/zypper support thanks to Robert Warmbier.
* A fix for #cmd_dir; directories were recognised as commands when their
  names matched. Thanks to Chris Heisterkamp.
* The 'xcode build tools' dep now tolerates gcc being installed in a
  separate location to the rest of the toolchain, to account for the
  case where it's installed separately via homebrew.

[My release deps played up, and created 0.18.1 directly on top of
0.18.0 without incorporating these changes. This version fixes that, and
merges the erroneous 0.18.1 commit so that 'stable' can fast-forward.]