Introduce more strongly typed SNatives and contract templates

Change case convention for permissions contract to match solidity style guide, add missing godoc comments, automate signature test

Refactor templating to util, move 'Solidity' types to a more proper abi package, improve documentation of permissions snatives and improve argument and return types

Introduce more strongly typed SNatives, templates for generating contract, and test for permissions contract

Cleanup: introduce word256 and remove dependency on tendermint/go-common

Function signatures automated and fix set global

word256: pull tendermint/go-common relating to word256 into eris-db for permissions and eris-mint (TODO)

genesis: re-introduce GenesisTime in GenesisDoc

Issue434: cleanup comments with respect to internal time

tests: add forced cleanup of :build tag

carry over hotfix: correct deployment from master and release

release: push latest from master, version tags from release, immutable version tag for tagged commits

Signed-off-by: RJ Catalano <rj@monax.io>

Signed-off-by: RJ Catalano <rj@monax.io>

Signed-off-by: RJ Catalano <rj@monax.io>

Signed-off-by: RJ Catalano <rj@monax.io>

issue-476: return One256 for EXTCODESIZE on native contracts

Signed-off-by: RJ Catalano <rj@monax.io>

Signed-off-by: RJ Catalano <rj@monax.io>

Signed-off-by: RJ Catalano <rj@monax.io>

Draft changelog

 Begin stabilising v0.16.0 on release-0.16

update JSON-RPC codec to observe specification