Colorful formatted SQL log output

To enable:
pip install pygments sqlparse
export INDICO_COLORED_LOG=1
Remove function-level * import
Refactor indico.core.db

- Anything SQLAlchemy-ish is in indico.core.db.sqlalchemy
- Every db.Model subclass now inherits the methods from IndicoModel
  (find, find_all, find_first, get)
Fix room photos

- Store photo id in Room (avoids query to check if there's a photo)
  instead of room id in Photo. REQUIRES NEW DB MIGRATION
- Removed all the old getSmallPhoto* etc. code
Remove strange inline Test class
Get rid of the __no_session_options__ magic

Import-time stack inspection is really not a nice thing..
Room map: Fix details link and photo
Always show a photo in room search results
Fix map of rooms cache
PEP8: indico.modules.rb.services
PEP8: indico.modules.rb.models

Some of the huge queries are left untouched...