Fixed the schedule event

In Android the ‘schedule’ event was not raised after scheduling one or
more tasks.

Warn against notification IDs that arent numbers

Fixed interval constant "hour"

The interval string “hour” had a typo: “houre”.

Master branch README.md is out of date!

Fixed Issue with date during convertProperties call in the update function.

Added more update-options
Revised try/catch blocks

Add new interface methods like exists, getIds, get

Close issue #38

Changed add-,cancel-, and clear function
Revised class-structure

fixed iOS 8.1 build fails with linker error #365