Adding table of contents for README.md

fix cmake error on macOS

Feature/175 async transactions

Fixed problems with doxygen groups and submit latest generated version

Contract integration test

Doxygen for wallet and currency contract.

Perfect README.md

Add Access-Control-Allow options

- Remove reference to the line that p2p is currently not implemented.

Improve code block highlighting as well as some other minor details.

P2P Linux platform fixes

Fixed formatting of GITHUB_USAGE_PROCESS.md

Changing travis to perform an out-of-band build

fix issues with missing construtors that strangely does not break locally even though it really should.  ref EOSIO/eos#175

fixed slow_test and api_test for out-of-band builds  ref EOSIO/eos#379

move transaction and message size limits to blockchain config so producers can vote on them ref EOSIO/eos#175

- connection now owns a fixed size send buffer, using only enough of it
to send each message.  Send buffer size matches input buffer size.
- network_version is now initialized in net_plugin_impl.