Update priv validator format in k8s to support tm v0.28.0+

Signed-off-by: David Dashyan <[email protected]>

Updated bigchaindb-abci (#2689)

* Updated bigchaindb-abci

Reason: gevent API change breaks BigchainDB installation
Signed-off-by: David Dashyan <[email protected]>

* Version bump

Signed-off-by: David Dashyan <[email protected]>

* Updated changelog

Version bump to 2.2.0 (#2682)

Signed-off-by: David Dashyan <[email protected]>

Transcation API extension: last_tx parameter (#2667)

* added last_tx switch to the TX get query to only get the latest TX for a given asset.
* extended test case to contain last_tx field
* Add last_tx option in query module
* Fix natural descending cursor sort argument

Fix bigchaidb-tendermint version mismatch

Last commit before v2.0.0b9 (#2608)

Last PR before the release of v2.0.0b8 (#2596)

Last PR before releasing 2.0.0b7 (#2576)

* Updated changelog for 2.0.0b7

* Change 2.0.0b3 to b7 in network-setup.md

* Updated k8s yamls for 2.0.0b7 release

* Updated version.py for 2.0.0b7 release

Problem: Election type not casted for runnign command (#2551)

Solution: Replace '-' with '_' before running election sub-command

Last pr before 2.0 beta 5 (#2430)

* Last PR before the release of BigchainDB 2.0 Beta 5

* Fix editing error

* Change development status back to 4 - beta

* Rephrase some fixes I

* Rephrase some fixes II