Simple map-reduce implementation in Golang

Lots of limits for the moment:

• single input file
• processes should be on the same machine for a shared local FS
• does not tolerate worker failure
• a single job at a moment

• Run a master go run wc.go master localhost:7777
• Run a worker go run wc.go worker localhost:7777 localhost:7778
• Submit the job go run wc.go submit examples/bible.txt localhost:7777

Alternatively the job can be run sequentially in a single process:

`go run wc.go sequential examples/bible.txt`

Result file is in the same directory as the input

`examples/mrtmp.bible.txt`

• Allow multiple jobs in parallel
• Decouple map and reduce function definition from worker, they should be part of the job definition and get submitted to workers
• Try out how to make use of mesos to run workers