Merge pull request #11 from marekjm/devel

New _sessiondelete() method
Initiaial code in `diaspy/connection.py` TODO list
`Connection()` object works, `diaply/client.py` partialy ported
Further porting on way to use `Connection()`
`diaspy` ported to use `Connection()` object
Small changes in `client.py` related to use of `Connection()`
Merge pull request #12 from marekjm/connection

Connection
Created new `diaspy.errors` module which will be responsible for
handling errors and define custom errors for `diaspy` to raise
Stupid mistake
Fixed typo in `diaspy.errors.react()` docstring.
Manual entry for errors added in manual/errors.mdown
Small changes in manual for errors
Added `get_followed_tags()`
Removed `get_followed_tags()` - not this branch
Stream() object with some basic functionality implemented (plus manual
and tests)
Code beautifying (flake8)
Updated manual
Client() rewritten to use Stream() object
Small changes in Makefile and code
Stream() moved to `diaspy/streams.py`, Generic() stream implemented