Add android trybot slaves
Add android trybot slaves

Refactor slaves.cfg and increase number of android VMs in preperation 
for a longer cycle time from additional compiler targets and a zip step.


BUG=
TEST=


Review URL: https://chromiumcodereview.appspot.com/10780034

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@147259 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build