configure keepRunner from command line

[mouyang]

As discussed in #64 (comment) - keepRunner is currently hardcoded and needs to be edited manually to keep the client-side specRunner after executing the jasmine:allTests task.

Using grunt.option allows this value to be configured through the command line. This also maintains backwards compatibility because the absence of this parameter on the command line means the return value is false.

[kate2753]

We need little bit more clean up here. It's hard to debug code, since runner is using unminified dust helpers code. There are few other issues with they way it's currently set up.

Also, I would also encourage following what main dust project does with gruntbuild, so if somebody is contributing to both projects he or she does have to deal with two different build setups.

Main dust project uses grunt testClient task for this purpose. I've posted a pull request #69 to bring build for this project in line with core dust project.

[mouyang]

@kate2753, it sounds like you would like me to wait until pull request #69 happens and before this one. I'm totally okay with that, let me know if that isn't what you want.

[sethkinast]

The specRunner will stick around if you use grunt dev instead of grunt test, which allows you to see what's output. Because it's ephemeral and gets rebuilt every time we probably don't want to trick you into thinking that you can make changes to it that would be kept.