Revert the last two commits

This solution did not work. I'll have to think of something more
elaborate.
bostree: Upstream update

Introduces new features required for solving bug #23
Globally lock the file structures for unique access

Whenever a file is somehow altered or needs to be accessed consistently
over multiple lines of code, lock a mutex. I've tried to avoid this, but
it seems that every other solution can be lured into a race condition.