Set alarm flag fixes and toast revision

Now properly allows the user to input something improper and correct it
without having to leave the activity. Also made the toast pop-up more
descriptive as to the format currently required
Check to make sure list is populated

When the shake clears the alarm and list it now checks to make sure
something is actually there
Centered the text in the current alarms listview

small change to appearance so that the list of alarms that are currently
set appear center in the listview