(Minor) Returning HTTP error code for bad-formed requests (no job_id passed)
* workerMetrics.R:
  - Using envars.R file to store local environment variables.
  - Retrieving the data from DB (instead of file_results.csv).
  - Uncommented parts of the code that used libraries (were temporarily disabled).
  - Changed passing of parameters (now it's compulsory, no example allowed).
  - Returning "JOB_NOT_FOUND" when the job_id parameter doesn't correspond to a valid job in the database.
* Simplify.R
  - Corrected bug for simplify function: when not all the "simple" relations were used within a job, there might be problems building the aggregated matrix (#columns < #Relations).

* Measures.R
  - Removed sentMat variable (not used) (min)
  - Changed "raw_data" parameter name to "dframe" (min).

* Envars.R
  - Corrected libpath env-variable. (min)
Merge branch 'master' of https://github.com/laroyo/watsonc