Added cipher_modes to main.c (should allow for change in mode)

TODO:
-test this change on a VM
-Add ability to switch to GCM
Add cipher mode to struct and use it.
Use cipher mode rather than global one
Set default cipher mode when initializing crypt_stat values
Copy global cipher mode name to cipher mode
Make previous commit abide by 80-character limit per line
Convert 4-spacing with tabs (for sake of consistency)
Added white list for cipher modes
Fixing errors and warnings from checkpatch.pl