Allow '%H:%M:%S.%L' format of time in Subtitle class
Merge branch 'master' of git://github.com/thiagokimo/srt-shifter into accept-complete-time-format

Conflicts:
	lib/srtshifter/subtitle.rb
Keep time convertion internal of Subtitle's shift method

This should remove errors from shifts made through srtshifter executable.
Ensure the right shift operation with '-%H:%M:%S.%L' time
Merge pull request #5 from Irio/accept-complete-time-format

Allow '%H:%M:%S.%L' format of time in Subtitle class