(maint) Add Travis CI Support

Without this patch facter has Travis CI configuration files, but they
don't seem to completely specify the dependency versions and the build
matrix.  This patch addresses the problem by putting the dependency
information in the conventional Gemfile location.

This patch should coincide with enabling Travis CI support for pull
requests.  A build status image is also included in the project README.
Finally, this patch also removes the Gemfile.lock since this shouldn't
be included in the repository as Facter is more of application than it
is a library.  This reverses the decision to include it, which was my
mistake, in 0b49eae and (#15464).
Fix Travis CI failures on virtualbox

Without this patch Travis CI has false positive spec test failures.
This is becuase the virtualbox utility methods are not properly stubbed,
causing other tests to execute in an unexpected fake environment.

This patch fixes the problem by stubbing out the
`Facter::Util::Virtual.virtualbox?` method.
Merge pull request #381 from jeffmccune/feature/master/travis_ci

(maint) Add Travis CI Support
Whitespace only reflow of README

This branch does not have a travis configuration file so I'm checking
the behavior of Travis when the branch is pushed to github.  I suspect
every single active branch needs a .travis.yml configuration file.
(maint) Add Travis CI support to active branches

Without this patch all active branches do not have proper Travis
configuration files.  This is a problem because Travis will exercise any
branch pushed to the puppetlabs organization repository on Github.  The
default behavior is to email notifications which is undesirable.

To address this problem Travis configuration settings are added to an
active branch.

Active branches are those that have recent activity when compared
against the following command:

    for k in `git branch -r |perl -pe s/^..//`
    do
      echo -e `git show --pretty=format:"%Cgreen%ci %Cblue%cr%Creset" $k|head -n 1`\\t$k;
    done | sort -r | grep origin

Which should produce output like:

    2013-01-06 11:01:40 -0800 3 hours ago   origin/1.6.x
    2013-01-05 23:33:48 -0800 14 hours ago  origin/master
    2012-12-27 10:03:43 -0800 10 days ago   origin/2.x
    2012-12-27 10:02:58 -0800 10 days ago   origin/1.7.x
Merge branch 'feature/1.6.x/travis_active_branches' into 1.6.x

* feature/1.6.x/travis_active_branches:
  (maint) Add Travis CI support to active branches
Merge branch '1.6.x' into 1.7.x

* 1.6.x:
  (maint) Add Travis CI support to active branches
  Whitespace only reflow of README
Merge branch '1.7.x'

* 1.7.x:
  (maint) Add Travis CI support to active branches
  Whitespace only reflow of README

Conflicts:
	.gitignore
	.travis.yml