OS and configuration specific integration test

Run integration tests with the -integration flag

Fixes race condition on jobs being done before handler is set.

concurrent map bug fixed #70

fixed #65

Allow built in selectionHandlers to be reused outside of package

Export SelectionHandler

Replace mutex in client.do() with a channel to avoid deadlock and int…

Updated to reflect new type names.

Fixed WORK_FAIL needing 2 arguments

According to http://gearman.org/protocol/ , WORK_FAIL only has 1 argument: the handle

Do not ignore write errors

Avoid read channel corruption when response size > bufferSize

When receiving a response, what was happening

1. Read bufferSize and it gets assigned to leftdata
2. Read another bufferSize
3. 2 buffers get appended, but leftdata still points to first buffer
4. Process data buffer which contains only complete responses
5. Back to ReadLoop, but leftdata still points to first incomplete buffer
    causing corrupt data to be processed

Solution is to make leftdata nil once we have merged it with the second buffer

When a job completes, remove its handler

Allow reconnect from error handler

Handling disconnects

Using the disconnect test showed the agent was silently closing on disconnect

gearman-go and original gearmand don't play well, possibly an issue?