Added in notification error checking

Notifications are now added, updated and deleted from activity.
Notifications are only checked if notifications are enabled in the app and are checked right after the values are inserted to the database.
Improved the StatusProvider delete commands to use the selection arguments.
Fixed up the precision handling for the notifications

Checking and displaying the notifications is based on the precision of the variable. Temperatures only have 1 digit of precision while PH has 2 digits and PWM percentages have no digits. No need to display the extra precision places if they are just zero.
Closes #61