Added tests for getRevisions and getRevisionInfo from page changelog

As preparations for #169 some unit tests for two changelog methods:
 - getRevisions()
 - getRevisionInfo()

Add a wikipage and its changelog metadata.

Some tests are still broken:
 - test_negativenum()
 - test_negativennumoffset()
 - test_zeronum()

These methods test `$num=0` or `$num=<negativenumber>` as argument for the method getRevisions().
The returns of getRevisions() is an array with all the revisions in the changelog or array with the whole readed chunk, but not an empty array. In my opinion an empty array is the desired result.

Current result is undesired, because:
 - at the moment the number of returned entries depends whether chuncked reading is used
 - zero should be zero, not something random.
 - negative range is nonsense. Sometimes one applies it to count from the end instead of the start, but that's also not useful here.

**Question**: Should the getRevisions() be improved?