fix storeconfig export for array values

For exported Resources with parameters which value is a Array the storeconfig export fails to collect them. Instead of collecting all the parameter values into a array it simply override the value with each value in turn.
Added tests around exporting storeconfigs with resources containing
arrays for param values.

Also added activerecord and sqlite to the Gemfile (currently the
storeconfigs tests are not running because those dependencies are missing).
Merge pull request #920 from senior/ticket/1.6.x/pdb-518-storeconfigs-export-arrays

(PDB-518) Fixing storeconfig exports containing arrays