v0.12.0

• (breaking-change) Refactor how drivers create connections. Allow creating Database without URIs. (#181, thanks @bcardiff)
• Close a transaction when returning from within its block. (#167, thanks @jgaskins)
• Fix race conditions in multi-thread mode. (#178, thanks @bcardiff)
• Allow the use of Enums when reading a ResultSet. (#168, thanks @jgaskins)
• Fix specs for Crystal 1.4 and 1.5. (#163, #173, thanks @straight-shoota)
• Update README. (#172, #180, thanks @amauryt, @jgaskins)

Note: The breaking-change introduced in this release does not affect consumers of the library, only driver implementors.