Add version to outgoing messages

- Added constant for version of release in constants.py
- Added 'v' value representing node's version number in send messages

This version number will help us see what version nodes are running on when diagnosing issues in the future.
Merge pull request #667 from hoffmabc/master

[CRITICAL] Add version to outgoing messages
Add timeout to resolve row lock bug

Simultaneous access to a row when writing and reading will cause an exception. This allows the proces to wait until it's available and then write instead.
Create only one zmq context to reduce overhead

Creating a zmq context for each PeerConnection object is wrong and creates a massive overhead.

Move context creation to parent class
Remove redundant context creation
Fix executable bit check to work on Mac OS X.

* Ignore results from virtualenv folder.
Merge pull request #672 from Renelvon/mac_checkstyle

Fix executable bit check to work on Mac OS X.
Rename 08 Web of Trust.md to 02 Web of Trust.md
Rename 09 Dispute Resolution in OpenBazaar - Arbitration Market.md to 04 Dispute Resolution in OpenBazaar - Arbitration Market.md
Rename 06 Voting Pools in OpenBazaar.md to 03 Voting Pools in OpenBazaar.md
Create 05 Notaries-pools-certification-blinding.md
Update and rename 05 Notaries-pools-certification-blinding.md to 05 Notary Selection in OpenBazaar.md
Update README.md
Update README.md
Create 06 Risk and Insurance in OpenBazaar.md
Update README.md
Update README.md
Merge pull request #682 from drwasho/master

Fixes to the Readme and addition of two new articles
Purge GNU LGPL headers from the codebase.
Merge pull request #670 from hoffmabc/master

Bug Fixes (single zmq context, timeout in database connection)