Move the cursor to the beginning of the line with C-a

[LockeAG]

Well I think this change is needed so we can use the same key binding to go to the beggining of the line.

# Change prefix key to C-a, easier to type, same to "screen" 
set -g prefix C-a   
   unbind C-b                                                              
   bind-key C-a send-prefix

That would fix the option to move the cursor to the beginning of line, just by doing C-a C-a