fixed auto-detect of Java step definition packages

(please hold before merging or even reviewing, still need some tests).

Before all directories would be proposed to cucumber; while this works it forced it to scan far more than necessary (e.g. 'com' package).

Also, now only the output resource dirs and package names are configured as glue dirs. Adding other source directories to the glue dir list should only be considered if meaningful (e.g. src/cucumber/ruby) i.e. it is language-specific...