More updates on examples and documentation, and fixes for Go 1.4

- Fixed many test cases where asserts were failing due to Go 1.4. It
  appears that in 1.3.3 a assert.Equal() of constant 10 and byte value
  can match, but in 1.4 it fails and I have to explicitly convert to
  int.
- Moved surgemq.go to cmd/surgemq.
- Added pingmq.go as a demo program to show how to use SurgeMQ.
- Organized README.md with additional details.
- Updated server.checkConfig to use sync.Once