ignore ruby-version and gemset
test ree and 2.0.0

also bit more verbose
test mysql2 in ar 2.3 and 3.0

also switch rubygems source to https
use fork/exec instead of pipes

and increase mysql startup timeout
use stubs instead of method definitions to allow running full rspec suite
minor polishing of config massage
add support for inactive connections

when connection is placed into inactive queue adapter will try to reconnect
every 5 seconds per connection in separate thread. if connection comes back
to life it's re-added to slave connections and is reused by application
immediately.

* current_connection is no longer cached in connection stack
* nil in connection stack means slave connection will be fetched
* on write connection stack is replaced with array of master connections
don't persist connection to master after write

empty connection_stack means default behavior - pick random slave, if
you want to persist master use #with_master
raise slave unavailable error and make connection inactive
prepare test helpers to run with multiple slaves
make tests pass with 2 slaves

also make sure connection error is checked on connection used for
sending query, not the random one
extract inactive queue into it's own class
attempt reconnects with configurable frequency, add spec
add integration spec for inactive queue