Loading external renaming css-map

[iflan]

Originally reported on Google Code with ID 33

New command line option '--input-rename-css-map-file'.
Ability to load a renaming css-map from external properties file added.
This is necessary if we need to create more than one compressed css-files that have
the same classes.

Reported by igor.demyanov on 2013-04-10 12:44:01