Add Support for Async requestCellInfoUpdate()

Add asynchronous calls to request CellInfo updates.
-Add a request for CellInfo
-Add a request for CellInfo that allows system apps
 such as the LocationProvider to bill the work to
 the app that initiated the location fix.
-Update the behavioral language for getAllCellInfo
 to indicate that depending on the API level of the
 caller, this API will only provide cached info, which
 means that apps can always request an update without
 possibly triggering a call to the modem. This also
 means that the binder will not block due to modem
 delay.

Bug: 37100068
Bug: 63737292
Bug: 26569588
Test: manual (via SL4A)
Change-Id: I25cbc3cecd5d396fc3baa21457c05cd6e273c9c3