Google Contacts 0.5.50b7

I ended the beta testing for Google Contacts 0.5.50 at b6 butI resume it since serious crash problem was found. It will happen when you install Google Contacts to a brand new profile. Please try v0.5.50b7 if you are faced with the issue. In addtion to the fix, it also includes minor bug fixes. To summarize up, it includes the following changes:

• Fixed: Thunderbird will crash when an address book window is opened
• Fixed: Progress bar does not stop when disk cache is disabled
• Fixed: Settings are not loaded to the option dialog when the account list is empty
• Fixed: Creating backup file for Thunderbird address books fails

v0.5.1x and before also involve the crash problem. I'm going to release v0.5.13 after the fix is verified.