Change details conversion WIP

Added Revisions database table to store change information that can change
 with each patch set
Added patchset number to FileInfo database table
Added virtual FileChanges table so we can query the file changes in a change
 and get the change's legacy change number
Added UserMessage class for querying change comments
Move last updated time from message to properties card to make querying
 easier
PatchSetChangesCard: Converted to use cursor
Modified deserializer to put revision details inside CommitInfo object

Change-Id: I9fcfaa1d8a02654ed9e98cf0eda1f39e1dd2eb05