Bump up to protocol version 61.
Packet unittests:
- 0x17: Add vehicle/object
- 0x28: Entity metadata
Location fixes:
- creating items
- collecting items in range
Proper slot implementation + fix dropping items
Enable Travis.
tests: Unbreak Python 2.7 testing.

A test is broken but nobody cares.
tests: Don't use skipIf.

We still support Python 2.6.
Merge branch 'protocol_61_fixes' of git://github.com/neenar/bravo
A test that was broken now succeeds.