Bumped version to 0.7.6

wrapper for mdb_env_set_mapsize (vhbit#46)

adding `set_mapsize` method to `Environment` which `wraps ffi::mdb_env_set_mapsize`
to allow resizing of maps on current environment

Bumped minor versions

Bumped version (0.7.3)

Fixed missed liblmdb upgrade

Bumped minor version to 0.7.1 (bitflags update)

Merge pull request vhbit#31 from vhbit/libc-upgrade

Upgrade to libc 0.2

Bumped versions

Bumped version

Bumped versions