Remove unnecessary files
MD5 asset file name suffix support in production mode
a change_log
new train usage interface

using Run function as a more clean user interface.
add tests for train#Run
ignore .sass-cache files
fix memory leaking probelm caused by ruby process
fix panicing public inexistence when bundlin assets
include compressed files to be listed in manifest.yml
fix ruby process killing bugs in interpreter pacakge
update handler tests
ignore .DS_Store files and introduce train.go as pacakge entrance
print message that is more understandable
add some comments
seperate development and production asset url parsing logic
update example
update readme
fix conflits
fix bugs caused by conficts