Mark proposals as applied on commit

This is another attempt for a fix of
https://bugzilla.novell.com/show_bug.cgi?id=861309

The previous solution was based on comparing the crowbar-revision of
proposal and the corresponding role. However, these numbers can diverge
arbitrarily and the comparison would not work as expected, as was observed in
https://bugzilla.novell.com/show_bug.cgi?id=877486

This patch uses a dedicated 'committed' attribute, which defaults to
false. It is set to 'true' after a proposal is committed and re-set back
to 'false' on any other operation.
Run brakeman automatically in travis

As we're already including brakeman in our gem bundle, it'd be nice
to actually run it automatically.

When we're green w/ the vulnerabilities, we can turn on the -z option
and let the build fail on new ones.
Merge pull request #1071 from bkutil/add_brakeman_to_travis

Run brakeman automatically in travis
Set the applied flag in proposal_commit

Instead of setting it in the controller, check for the return value of
apply_role in the proposal_commit ensure block, and mark the proposal as
applied accordingly.
Switch rspec format to nested
Merge pull request #1076 from bkutil/use_nested_format_in_rspec

Switch rspec format to nested
Pinned ohai version

While working with bundler for development it tries to install ohai 7
without this version constraint and the new ohai version is not the
version we currently want to ship and it produces some warnings on the
quite outdated ruby 1.8 version.
Merge pull request #1078 from tboerger/feature/ohai-version

Pinned ohai version
The attribute name is the same in barclamp and UI
Added more strict gem version constraint

I have added a more strict version constraint because the previous
versioning doesn't work if you work on the git base. If you bundle
install in the crowbar_framework folder it always installs upstream chef
10.32.x and ohai 6.22.x. Installing this chef version breaks pacemaker
as it works with subfolders on libraries folders, these files won't get
uploaded to the chef server with upstream chef client.
Merge pull request #1079 from tboerger/feature/gemfile-constraints

Added more strict gem version constraint
Add applied attribute
Merge pull request #1081 from bkutil/add_applied_attribute

Add applied attribute
Merge pull request #1068 from bkutil/proposal_applied_check

Mark proposals as applied on commit