First pass at new interfaces for pipelining
New appendFuture
First pass at pipelining for network transport
First pass at pipelines for inmem transport
Adding test for network transport pipelining
Inmem transport copies the result in the pipeline
Support a timeout in the net transport
Seperate read/write deadlines for pipeline
Better support for timeouts in the pipeline
Adding a Start() time to AppendFuture
Close replication channel after sending final index
First pass at pipelining support in replication
Refactoring replication code
Increasing test reliability
Increase ceiling of in-flight append entries
Increase various timing allowances
Fixing integ test
Merge pull request #15 from hashicorp/f-pipeline

Adding support for pipelining of AppendEntries