Triggered execution of sbt run

[hariharansrc]

Is your feature request related to a problem? Please describe.
Currently sbt process and application process are same.
When application is exited sbt will be killed.
Run sbt separately such that we don't need to wait for sbt load for every run.

Describe the solution you'd like
Fork the application process for every run. It is available in sbt.version=1.1.1, but there is command line issue when exiting the application. In sbt.version=1.2.7 it is working well.

Describe alternatives you've considered
There is plugin named https://github.com/spray/sbt-revolver. Need to evaluate whether it adds any thing extra.

Additional context
NA

[hariharansrc]

To run using triggered execution

1. Run sbt

sbt

2. Triggered execution

~run

3. Application can be exited normally by pressing Enter. New changes will be compiled and application starts again.

[bhermann]

Closed with #40