remove unneeded dependencies (tilt, thread_safe, slim)
set version to 1.5.0.alpha.3
Release 1.5.0.alpha.3
swap yield with instance_exec to workaround issue in JRuby
set version to 1.5.0.alpha.4
add note about fixing nested keep_together
Release 1.5.0.alpha.4
prepare for next development iteration