mGerrit: Fix PrettyPrint of Dates

Also now getting the last modified date requires Context
Context is used to get the 'at' word from the resources.
This allows for translators to do their thing.
 + allow for Internationalization of words within date formatting

Patch Set 3: include Locale when creating the pattern
Patch Set 4: TimeZone.getDefault() is not always accurate
             to make up for this shortfall we allow the
             user to provide the localization

Change-Id: If5b4871e724b5625d3bf6e79d88d7cef377ecaf4
Merge "mGerrit: Fix PrettyPrint of Dates"