fix: reporter allow using a externally provided source cachere for reporters

[weikinhuang]

change coverageReporter options to allow for specifying sourceStore, this
is an instance of istanbul.Store to look up source files. This allows using
external coverage collectors like browserify-istanbul for instrumenting code.

references #16, #123, #124

[weikinhuang]

This pull request allows for specifying an external source cache storage in karma.conf.js

module.exports = function(config) {
  config.set({

    coverageReporter: {
      type: "html",
      sourceStore: require("istanbul").Store.create("fslookup")
    }

}

[weikinhuang]

also, can someone take a look as to why the travis build failed?

[vperron]

did it ?

[dignifiedquire]

Travis looks happy, but this needs a rebase onto the latest master, as there are merge conflicts

[weikinhuang]

rebased

[dignifiedquire]

Could you add some documentation about this please?

[weikinhuang]

sure

[dignifiedquire]

stilll missing docs and rebase

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[weikinhuang]

I signed it!

[googlebot]

CLAs look good, thanks!

[dignifiedquire]

lib/reporter.js 100644 → 100755 looks like you accidentally change the file permissions for lib/reporter could you revert that please?

[weikinhuang]

fixed

[dignifiedquire]

@weikinhuang I'm afraid I need another rebase, another merge conflict while I merged a different PR, thanks

[weikinhuang]

rebased

[dignifiedquire]

Thanks