allow specifying formatters for dimension values

[devvmh]

I'm still testing this out; I'll push updates if I have any problems.

Given a dimension specification like this:

{
  "name": "is_this_record_interesting",
  "cardinality": "tiny",
  "info": {
    "cv-format": {
      "0": "False",
      "1": "True"
    }
  }
}

Now for example, using an SQL backend, a column with the given name will have its values translated by cubesviewer to read True or False, rather than 0 or 1.

[jjmontesl]

Closing this. If implemented, shall be using cv-formatter on the dimension, calling a custom javascript function or evaluating in place. This custom mapping structure adds complexity that generic formatters shall be able to solve.

Also, new pull requests shall be sent please against the devel branch (not very stable atm).