smw.dataItem() JavaScript Prototype classes

The change enables to represent dataItems as objects rather than
strings while working with/through the SMWAPI.

## Classes

++ smw.dataItem.wikiPage
Using the same identifier(fulltext, fullurl, namespace) as in the SMWAPI
serializer which makes object mapping simpler.
++ smw.dataItem.uri( fullurl )
++ smw.dataItem.time( timestamp )

## Example
var wikiPage = new smw.dataItem.wikiPage( value.fulltext, value.fullurl, value.namespace );
wikiPage.getHtml( parameters.link === 'all' || parameters.link === 'subject' )

## QUnit
++ ext.smw.dataItem.test 1 tests of 1 passed
++ ext.smw.dataItem.wikiPage.test 24 tests of 24 passed
++ ext.smw.dataItem.uri.test 8 tests of 8 passed
++ ext.smw.dataItem.time 8 tests of 8 passed

Change-Id: I3f4b522bc48e957d24048103241efe8ddf8d5913
Merge "smw.dataItem() JavaScript Prototype classes"