work around noisy 'conflicting chdir during another chdir block' warnings

If the popen method is used with the :chdir option within a Dir.chdir
block on ruby 1.9 (fex inside a in_build_dir block), a warning is issued that is needless distraction here
since we're about to exec anyway.

See the implementation of Dir.chdir
http://www.ruby-doc.org/core-1.9.3/Dir.html#method-c-chdir
Remove unused start_at arg from String#colorize!.
Merge remote-tracking branch 'bearded/colourise-bang-fix'
Fixed Travis rbx check
Make the rbx-specific gems available in all groups, not just test.
No need for gemfile version constraints; the lockfile's got 'em.
Ignore rbx's bin/irb.
Merge branch 'rbx'
Added test: accepts_*_for accepts_list_for should return the correct boolean default when no value is stored
This is an accepts_value_for spec: expect values, not arrays.
Correctly return an AcceptsListFor default of `false`.

A falsey default would previously fall through to the empty list, which AcceptsValueFor would shift, returning nil. This correctly returns `[false]`, which produces the correct default in AcceptsValueFor.
Merge branch 'accepts_value_for-boolean'
Add Debian 7.3 / wheezy codename support.

Signed-off-by: Laurent Vallar <val@zbla.net>
Merge pull request #302 from Val/add_7.3_wheezy_debian_version

Add Debian 7.3 / wheezy codename support.
run add-apt-repository and apt-get update as root
Merge pull request #303 from santouras/master

Adding PPA's fails if not being run as root
Use PathHelpers.cd to wrap the chdir logic and avoid two exec calls.
Merge branch 'chdir-warning'
`writable?` -> `writable_real?`

Fixes subtle issues with writable detection, see:
https://github.com/Homebrew/homebrew/commit/8aa4f9dd3bbd885350776171d3d9
Updated Debian 7.4 (wheezy) has been released, see http://www.debian.org/News/2014/20140208

Signed-off-by: Laurent Vallar <val@zbla.net>