CBLT-202:  cd to correct directory to run start_android_emulator.sh, etc.

Change-Id: I38e399d127833304777e873d72c28fb07de0da5c
Reviewed-on: http://review.couchbase.org/34704
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>