Handle error messages caused by missing binary libraries.
Improves sudo propmt
Use http:// instead of git:// on GitHub URL's
Refactor parallel worker code and make it work on jruby
Add parallel worker documentation

Also added --jobs option to man file
Push a fix for SharedHelpers.chdir not being threadsafe

The platform detection is a bit messy and I will refactor it later
Use newly introduced current_ruby method for platform
Start adding specs for bundler parallel install
Add check for JRuby apart from Windows on build_extensions method
Add separate specs for parallel gem installation
moves CONTRIBUTE.md to DEVELOPMENT.md
updates link to DEVELOPMENT.md in CONTRIBUTING.md
updates DEVELOPMENT.md dbundle alias to be more general
Do not use parallel installation on unsupported systems

1. Use parallel installation on MRI if asked.
2. On non-MRI check for rubygems version that is threadsafe
Add --quiet option to bundle package
Newer versions of Rails are not installable for old rubies or RG

Install Rails 3.2.13 parallely in test case
Switch from installing Rails to faker & AS
remove unhelpful vendor update task
Update to erikhuda/thor@2b347d4363c9b1bfeb4de2426d5c4edb054f2ced
Update to drbrain/net-http-persistent@7dcbf7cd08ac8ad62426c11840cba3a40d8a42a8