changed: all constants in araby.py are now in araby_constants.py and imported into araby.py
changed: araby.py module now only have functions, no class araby
More fixes, tests, docs and refactoring

added: more tests with helper functions for tests as well
fixed: isTashkeel using undefined variable
edited: some functions refactored
Merge pull request #378 from Ahimta/master

Moving constants in araby.py to a new file araby_constants.py
add Meriem.bnf to AUTHORS list
Merge branch 'master' of github.com:Alfanous-team/alfanous
Merge branch 'master' of github.com:Alfanous-team/alfanous into corpus
move the araby constants inside Araby