Add translation support to upper level modules

Added translations into modules:
 * sahara/main.py
 * sahara/context.py
 * sahara/config.py
 * sahara/exceptions.py
 * sahara/db/sqlalchemy/api.py
 * sahara/service/edp/binary_retrievers/internal_swift.py

Added change to tox.ini in section [hacking]
for pep8 passed

Change-Id: I8b1e3f5ec58798b48b992dc8c42ce366256f8099
Merge "Add translation support to upper level modules"