Kill a kernel when the user leaves the page

Other changes to the API
Create Multi-Mechanize tests
Use msg_type in message header
Modify .gitignore for v2 at top level
Merge pull request #355 from ihanson/multimechanize

Multi-Mechanize tests
fix whitespace
Store the language and code with the shortened permalinks.
Make the web database work
Make sqlalchemy callback-oriented
clean up
Properly import the db file depending on the config
Add permalink server config
clean up permalink server code
clean up permalink server
get code *after* codemirror has saved it