Remove English compiled catalogs after compilemessages

./run_tests.sh --compilemessages compiles all languages including
English, but English is the source language and there is no need
to have compiled message catalogs for English.

Also this commit update the description of --makemessages.

Change-Id: I30cf4336cc796e8e3bea71120b6c75ce40aaf888
Closes-Bug: #1261290
Merge "Remove English compiled catalogs after compilemessages"