TelemetryScheduler: add a save button

Previously you had to load the settings to the UAV every
time you started it.  This makes this gadget of pretty
limited usefulness.  Now you can save the settings persistently
to the UAV.
TelemetryScheduler: make sure to remove the ms suffix from rates

The telemetry scheduler was totally broken because the rate suffix was
not always removed and thus some strips failed to parse into valid
integers.  This creates a function to perform this and uses it consistently.

Fixes #679
Merge pull request #679 from peabody124/telemetryscheduler_save

TelemetryScheduler: add a save button