Added other common acronyms

Added acronyms for:

- be back in a bit
- be back in a flash/few
- be back soon
Removed bbs as it is ambiguous with 'bulletin board system'.
Merge pull request #1226 from monokrome/patch-2

Added other common acronyms
Add more error checking, and more descriptive reasons for failure
Merge pull request #1230 from github/meme_generator_errors

[meme_generator] Better error handling
Version bump to 2.5.7