README review , most importantly :
* added notes on executable/runnable feature support (#136)
* removed notes on Merb support (JRuby-Rack will remove Merb support completely + it's been most likely non-working in 1.1.x releases anyway)
* expect "compiled" .rb to be changed to do a load instead of require - this has been a long incompatibility issue and is present in #134
Merge pull request #138 from kares/readme

README review