Migrate to flake8

Working on Turpial/libturpial#33 issue. Until now we covered
the following tasks:

- [x]      E501 line too long
- [x]      E302 expected 2 blank lines, found 1
- [x]      W291 trailing whitespace
- [x]      W391 blank line at end of file
- [x]      E128 continuation line under-indented for visual indent
- [x]      F401 imported but unused
- [x]      F403 unable to detect undefined names
- [x]      E127 continuation line over-indented for visual indent
- [x]      E231 missing whitespace after ':'
- [x]      W601 .has_key() is deprecated, use 'in'
- [x]      E251 unexpected spaces around keyword / parameter equals
- [x]      E303 too many blank lines (2)
- [x]      E126 continuation line over-indented for hanging indent
- [x]      W293 blank line contains whitespace
- [x]      E301 expected 1 blank line, found 0
- [x]      E261 at least two spaces before inline comment
- [x]      E711 comparison to None should be 'if cond is not None:'
- [x]      E203 whitespace before ':'
- [x]      E701 multiple statements on one line (colon)
- [x]      E225 missing whitespace around operator
- []       F841 local variable is assigned to but never used
- []       F821 undefined name
- []       F999 syntax error in doctest
Some improvements to send_tweet example

- [x] Handling the exception when libturpial is not in the sys.path
- [x] Now it's possible to parse arguments from the command line
- [] Support for identi.ca protocol
Migrate to flake8
Libturpial: Use https by default for twitter api

See https://dev.twitter.com/docs/security/using-ssl for details
Merge pull request #88 from Skunnyk/https

Libturpial: Use https by default for twitter api
Set version numbers in requirements.txt
Fixed exception in line 308 of config.py
Fixed get_list_id method in account model
PIN stored no more
Fixed flags variables on status model
Fixed broadcast with empty or none account_id array
Fixed cache calculation
Updated load function for oauth credentials
Fixed issue with verifier removal
Added new field in status model to store original timestamp from twitter
Loaded account after register
Added followed_by field to profile in order to know if user is followed by the profile owner
Added and removed friends from local list after follow, unfollow, block and report as spam
Fixed delete cache method
Removed unnecessary information