Merge branch 'jc/push-cas' into pu

* jc/push-cas:
  WIP: pass cas option down to transport
  remote.c: add command line option parser for --lockref
  push: beginning of compare-and-swap "force/delete safety"
  remote-http: use argv-array
  builtin/push.c: use OPT_BOOL, not OPT_BOOLEAN
  cache.h: move remote/connect API out of it