Support multiple commands

[danielbeardsley]

We want to be able to support cimpler running several commands are reporting each one as a separate CI status / log.

Suggested Implementation

Config

Instead of command: "some command":

/**
 * A list of shell commands that will be individual builds created
 * The exit code of this command determines success or failure    
 * of the build. Both stdout and stderr are sent to the log.      
 */
buildsTasks: {
   "Unit":        "test-suite ...",
   "Integration": "test-suite ...",
   "Image Diff":  "test-suite ...",
},

When injecting a build, inject one build for each of the above commands. Include the key name "Unit" and so on as build.processName or something so the commit-status plugin can use that when reporting the status.