rhbz995910 - Change transaction successful event to immediate.

Because transactions are being handled manually, a transaction successful event will fail when raised.
Add better error checking when importing invalid TMX files
Merge pull request #116 from zanata/rhbz995910

rhbz995910 - Change transaction successful event to immediate.
Merge pull request #118 from zanata/handle-invalid-tmx

rhbz995909 Add better error checking when importing invalid TMX files