Adding flags to facilitate cross compiling to ARM

Empty Call response should return 0x instead of 0x00. Closes #739

Changed "Welcome to the Frontier" to something more geeky

Issue 777

Rename eth_Version to eth_protocolVersion. Closes #737

Revert "Revert "refactor Dockerfile""

Revert "refactor Dockerfile"

refactor Dockerfile

Win32 build fixes

These changes ensure that the JS tests run without networking
and fixes the block chain export and its associated test.

This helps with fixing the tests for cmd/geth to run without networking.

64bit atomic operations are not available on all 32bit platforms.

The test is failing the 32bit build and the function
is not used anywhere.

Further fixes to block test wrapper

Treat hexnums as big.Int instead of int64. Closes #762

core: transaction fixes

Block test improvements

You can now specify `null` as a way of saying "not interested in this
topic, match all". core.Filter assumes the zero'd address to be the
wildcard. JSON rpc assumes empty strings to be wildcards.

Remove "minGasPrice" field from JSON responses. Closes. #754

All nonce error handling has been moved to the worker

When worker encounters a gas limit error, subsequent txs should be
ignored from that particular account. This will prevent:

1. Nonce errors been thrown all around
2. The "Known tx" error. Closes #719
3. Repeated contract address. Closes #731

* Move go test wrapper for block tests from cmd/geth to tests
* Fix logic for when tests are valid or not, by adding correct
  validations for expected valid/invalid blocks
* Change block insertion helper to work on single blocks
* Add one test case for each file in BlockTests and comment out
  the tests which are currently failing
* Add Skip call in all block tests in lieu of performance fixes
  around ethash cache which are needed before it will be fast enough
  to start / stop the node between each test

trivial fix for: Broken link for detailed go build instructions #661