Bump to 0.6.4 dev.
Bump to 0.6.4 dev.

davidt/rbtools,haosdent/rbtools,haosdent/rbtools,halvorlu/rbtools,datjwu/rbtools,halvorlu/rbtools,datjwu/rbtools,datjwu/rbtools,haosdent/rbtools,beol/rbtools,beol/rbtools,davidt/rbtools,reviewboard/rbtools,davidt/rbtools,reviewboard/rbtools,halvorlu/rbtools,beol/rbtools,reviewboard/rbtools