Updated web and file access helper classes

* Moved classes to util package
* Changed main interfaces from BufferedReader to InputStream
Move mock object code to new testing module

Otherwise one would either need to have a dependency on Mockito for the
utils package or move the mock objects to the test directory of that
package.
Extended tests for web/file mock classes
Extended documentation
Merge pull request #33 from Wikidata/web-file-utils-cleanup

Web file utils cleanup