repopick: add -b shortcut option

  * useful for people like me who want to pick into temp branch so
    that the picks survive a repo sync
  * shortcut to "--start-branch auto --abandon-first --ignore-missing"

Change-Id: Ia4d4309d27e46a15ff4b74525668d974f4251dcb
repopick: handle additional error cases around subprocesses

  * gracefully error if the project path cannot be found
  * poll() was not a reliable determination of EOF on my
    Darwin-Python 2.7 system.

Change-Id: I203c2a75820f8acc079a5c9751d1c04daf6f3a16
repopick: allow running from a subdir of ANDROID_BUILD_TOP

Change-Id: I6dfcd5dfe700174ed87dc8627b23519c62b4cb27
s/cyanogenmod.com/cyanogenmod.org/

* And fixup a wiki link while I'm at it.

Change-Id: I0355b9a47eac1becc07e81659fbb2d11b14ece36
envsetup: hmm repopick

Change-Id: I483cb36721f31dbf1f67e46cbe8a306b2a9e2c15
repopick: decode the result as UTF-8

Change-Id: I51f2defa861c86b51baa7bad1df1d9666b952160