Updates to documentation and .deb building

Updates to build .deb

Now builds a .deb and .rpm capable of using the new openbazaar launcher.

Had to modify the bash launcher so that it changes its current directory
over to openbazaar's installation folder in linux. May have to add
checks for OSX later, although I believe in OSX, this script will be
irrelevant as the application will be launched via .app launcher.
Migrate to bitcoin from pybitcointools. Fix #552.

* Replace privtopub with privkey_to_pubkey.
Merge pull request #842 from Renelvon/bitcoin

Migrate from pybitcointools to bitcoin.
Do not log image data in any circumstances
Silences unnecessary error log on shutdown.
Merge pull request #851 from gubatron/transport-shutdown-fix

Silences unnecessary error log on shutdown.
Merge pull request #848 from dionyziz/log_no_images

Do not log image data in any circumstances. (part 1)
fix/remove incorrect add_known_node() call

this should be (uri, pubkey, guid, nickname) but add_peer() will call
add_known_node() anyway, so just remove this call

Signed-off-by: Thomas Stilwell <stilwellt@openlabs.co>
make DHT::add_known_node() private

Signed-off-by: Thomas Stilwell <stilwellt@openlabs.co>
Merge pull request #865 from benemorius/fix-add-knownnodes-call

fix/remove incorrect add_known_node() call
Release checklists
Merge pull request #846 from dionyziz/contributing_release

Release checklists
Merge pull request #832 from gubatron/launcher-documentation-updates

Update launching documentation. Fix debian package (part 1).
Refactor and test init_additional_STUN_servers.

* Make it accept any server sequence.
* Make it idempotent.
Test and refactor.

* Import modules, not names.
* Stricten port tests.
* Rename check_NAT_status to get_NAT_status.
* Test is_ipv6_address.
* Fix docstrings and test get_peer_url.