universal_archs returns ArchitectureListExtension
Skip the check for Xcode on non-OSX systems
git: Disable OS X keychain helper Closes #1
GCC is named gcc-4.2 on MacOS and gcc elsewhere
brew update: Pull from the branch linuxbrew

Taps still pull from the branch master.
Closes #4
Disable m32 and m64 on non-OSX systems. Closes #8
Replace the README for Linuxbrew

Add some basic documentation.

Closes #10.

Add ruby 1.8.6 requirement

For now, it seems that homebrew-core requires Ruby 1.8.6

Known limitations of Ruby 1.8.5:
* RUBY_PATCHLEVEL is not defined
* instance_variable_defined? is not defined
* pathname.rb:223 - 'Digest::SHA2' => 'Digest::SHA256' is necessary

Closes homebrew/linuxbrew#12
Closes homebrew/linuxbrew#15

Add instructions to set LD_LIBRARY_PATH in .bashrc

Closes #9
Skip the compiler version check on non-OSX systems

Closes homebrew/linuxbrew#5
When the root cache is not writable use home_cache

The home_cache is `~/Library/Caches/Homebrew` on MacOS and
`~/.cache/Homebrew` on other systems.
Closes Homebrew/linuxbrew#17.