added ability to add item by OfferListingId
doc comments block alignment
Merge pull request #28 from dmaslov/master

added ability to add item by OfferListingId
Set configuration on request class.
Added functional testcase.
Removed setUp-method to skip only the functional test.
Tweaked RequestFactory Test to ensure the right configuration object is passed.
Removed unused code section
Adding ability to search by using SKU, UPC, EAN and ISBN.

All test passed and look good.
Update code to throw exception instead of let's it pass through.
Using constant for idType and combine Exception into one line.
Merge pull request #31 from apzentral/master

Adding ability to search by using SKU, UPC, EAN and ISBN. (Updated Code to use InvalidArgumentException)
Merge pull request #1 from Exeu/master

Merging updates