Refactored the way environment is prepared in JRubyExec (to less lines of code)
Address path variable in a platform-sensitive manner when preparing the JRubyExec environment
Refactored computation of a working search path when using GEMs so that it works properly in a cross-platform manner
project.jrubyexec now uses the same environment preparation as JRubyExec
Made sure that if getGemWorkDir changes value, that JRubyExec will rebuild