Emulator script improvements: config templates, --api-level, and mips support.

BUG=

Review URL: https://codereview.chromium.org/72383005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236219 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236219