Enhancements to workload scripts

Enhancements to workload scripts

- display frame latencies (90th/95th/99th) for recents and systemapps
- allow device type to be specified to capture
- workaround for am hang when starting chrome on volantis
- bullhead support for recentfling

New output of "recentfling.sh":

Fling recents...
Frames: 772 latency: 19/22/34 Janks: 131(16%)

New output of "systemapps.sh -T":

App      Start(ms) Iter(ms) Jank      Latency
gmail       1090    2168      69(72%) 65/75/88
hangouts    1757    2758      60(82%) 69/111/114
chrome         0     997      59(64%) 68/77/84
youtube     3533    4834     140(48%) 70/93/150
play        1868    3147      92(62%) 89/106/182
home           0    1125     210(15%) 62/84/129
TOTAL       8248   35052

Change-Id: If4fc94ab0188dae2afabfbf696be06b6ddf55ce1