Upgrade to bitcoinj 0.17-alpha1, ConsensusJ 0.7.0-alpha1

[msgilligan]

TODO:

• [ ] Investigate possible intermittent failures in regTest -- deferred see Issue #229.
• [x] Review OmniAddressMainNetParams, OmniNetwork, etc. (It would be nice if bitcoinj had pluggable address formats and could have multiple address formats on the same network or something like that)
• [x] Look more thoroughly for use of deprecated methods
• [x] Output value issues, 2 ignored tests: BitcoinJTransactionBuilderSpec, EncodeMultisigSpec -- workaround for bitcoinj 0.17 issue applied.
• [ ] Global/consistent use of OmniAddressParser -- deferred until later bitcoinj release and/or Omni Core segwit support
• [x] Convert OmniCore clients to use Network in constructors
• [ ] Address(Key)DeserializerSpec null/wildcard network specifier issues in Jackson module -- deferred
• [ ] Migrate @Ignore'd unit tests that are actually regTests to regTest -- deferred

All TODOs are now either complete or deferred

[msgilligan]

Because this PR is large and contains 7 commits, I will use a "merge commit" to merge it.

[msgilligan]

Thanks @dexx! Merging...