Corrected 'collection_key' and 'key'

Changed the 'collection_key' in LanguagePackManager
for sending a correct language pack url to solum-api.

Changed the 'key' in LanguagePackManager for correctly
parsing language pack 'show' and 'delete' commands.

Fixes bug 1310749

Change-Id: I3025b15ea25cbcedf61fece6a50db3805db95ba9