Introduce compiler information framework

Introduce functionality to detect the available compiler types, versions
and targets.
Revamp patching functionality and add clang patches

This commit fixes #94 and closes #105
Stop using RUBY_PLATFORM
Update Rubinius version in .travis.yml

Travis now supports only Rubinius 2.1 and
up. http://about.travis-ci.org/docs/user/languages/ruby/#Rubinius

Additionally the Ruby standard library has been separated from rbx in to
a set of gems and now needs to be set as a development dependency.
http://rubini.us/2013/09/22/ready-set/
Merge pull request #110 from ignisf/compiler-detection

Introduce compiler information functionality