All constant STEEM and SBD strings inside beempy are replaced by steem.steem_steem steem.sbd_symbol properties

* Fix test_block unittest
* Adapt Changelog for next release

remove debug print

account.py: fix potential ZeroDivisionError

refs #99

closes #99

Fix typo in documentation

Fix get_discussions infinite cycle when discussions are empty

This is a common mistake, its vs it's
Read about it at http://www.elearnenglishlanguage.com/blog/english-mistakes/its/

Scheduled weekly dependency update for week 39

Fix `Discussions_by_author_before_date` in `get_discussions`

Account
* some code improvements
Graphenerpc
* small improvement in chain detection
Steem
* replace_steemit_by_steem option removed from get_config
* witness_update fixed
Comment
* Fix docu
chain
* Waleshares added
Unit test
* unit tests fixed

corrected typo

European Financial Transparency Gateway support in Beem

* add claim_account RC calculation
* fix Bytes type
* Improve testnet example
* test_types improved

Using generic asset symbols