feat: InstantLock class (#194)
* add class InstantLock
* register class ChainLock in bitcore
* add tests
* fix: use inlock prefix
* use instantSend quorum type
* test for inlock prefix
* impr: test description
* fix: change prefix to 'islock'
* fix: some tests
* fix: validation
* add instant lock diff fixtures
* refactor tests
* fix getRequestId
* clean up fixtures
* tests: add correct quorumEntry vector
* reintroduce getSignHashForQuorumEntry
* refactor verification
* bump version
* update package-lock.json
* fromHex: reuse fromString method
* up verify test timeout for travis
