Update arcapi.py

Filip,

I have added all my new functions at the end.  I am not sure if this is the correct pull request (I think this is patch 2?).  Let me know if I need to make the changes elsewhere too.

Caleb
Update arcapi_test.py

Filip, 

I added tests for my new functions. Could you add the testing data I emailed so my tests work?  I didn't see anywhere that I could upload the data.  Thanks.

Caleb
Commit Caleb's arcapi.py before merge
Commit of merged arcapi.py
Merge pull request #5 from NERC-CEH/CalebM1987-path-2

Merge Caleb m1987 path 2 to NERC-CEH master