Consolidate SMS messages

[lizzyaustad]

Instead of repeating the logic and error catching each time we need to send an SMS, we should have one method called send_sms that accepts parameters for the phone number to send to and the message to be sent to that number. It should follow the try/except pattern currently in the test_text, initialize the Africa's Talking and SMS services, and print the response message. We should also add a validation check that the number we are trying to send a message to starts with a + character and add one in if it doesn't.