fixed doc
fixed android build module, when keys file is not presented in global config file, or even global config file is not presented
check version value in bump_version module. abort build if its value isn't correct
added configurations existence check from inheritance tree in config loader
add support for mac applications
Merge pull request #5 from pingwinator/master

mac apps
cleanup code formatting
check if apk file exists in copy_apk module
updated docs for build_android module
expand file path to file with data for ant.properties
added shell method for safe shell calls
moved fail method to BaseModule class, added to its output classname. added info method for logging. setting module's config to empty hash if it not presented
updated all calls "puts" to "info"
removed INFO word from output in info method, now it looks clearer