Clock application now has launcher shortcuts

Bug: 28581133
Bug: 29875092

Long pressing on clock with a supported launcher will bring up
a list of 4 shortcuts: Create new timer, create new alarm,
start/stop stopwatch, and start clock screensaver. Analytics on
shortcut use are reported.

Change-Id: Iea7e05024218f70d2bec4bef1357dd8afa0165e6