Adds a method to get the latest version number to AlgorithmFactory. This
is used by the two script building algorithms to determine if a the
algorithm version needs to be included in the history

Adds a method get a single descriptor in the Algorithm factory, this
avoids us having to get all algorithm descriptors. Each time we want a
descriptor every algorithm object is allocated (900+) then discarded for
each workspace

re #8120

It provides easy access to the highest version of an algorithm
currently registered.
Refs #9521

The compliers were complainign about a conversion from size_t to int, so i changed it to top them complianing

Refs #3344

A new fake algorithm has been added to help test the category methods.

The Test suite has been completed with tests for all methods and error cases where applicable

Refs #3344

The test suite is coming along, only a few more tests to write

Refs #3344

Susbscribe now has a test.
A second testCreate was deleted.

Refs #3344

The AlgorithmFactoryTest.h file has a skeleton in there now ready for the tests

AlgorithmTest has had a bit of code refactored into it's own .h file. They are "fake" algorithms specifically for testing.

Refs #3344