Added 'useDoubleNumbers' configuration parameter
Added 'useDoubleNumbers' to select the type (float or double) for schema type 'number'.
Essentially, replicates the same behavior as 'useLongIntegers' but for 'number' type
Added tests for 'useDoubleNumbers' and other minor changes
Merge pull request #135 from anserran/master

Added 'useDoubleNumbers' configuration parameter