Fixed logic error in Encrypt Function

I noticed a logic error that i gave you since it was different than what i have
if you do
for i in range(len(m) - 1):
M = (ord(m[i]) * 128) + ord(m[i + 1]) 
then M will be reset every time
For example
The string 123 to base 10 would go
M = 10 + 2 (i = 0)
M = 20 + 3 (i = 1)
leave loop
M = 23
Merge pull request #1 from mjc118/patch-1

Fixed logic error in Encrypt Function