Creates IFluentEnumerable and IFluentString + update some unit tests.
Deletes the StringExtensions class and makes unit test leveraging on the IFluentString methods instead.

Adds some headers to previously added files.
Migrates from extension methods to IFluentAssertion or IFluentString interfaces (note: unit tests and styleCop are failing).
Fixes the unit tests that were broken during the first session of the design breakthrough.
Restores a  previously commented unit test.
The IFluentEnumerable interface has now the method: Contains, ContainsOnly and ContainsExactly (and no more a Properties method which is now a IEnumerable extension method again).
Fixes 2 unit tests related to the IFluentEnumerable.ContainsExactly method.
Introduces a backlog file.
Adds a UseCases.md file.
Includes the new Backlog.md and UseCases.md files to the solution.
Improves presentation format of the UseCases.md file.
Gets rid of useless generic type parameters within unit tests.
Refactors and cleans the Assert static class (including documentation).
Migrates the EnumerableRelatesTests to the new NFluent design.

Makes fluent methods returning void instead of bool for the IFluentEnumerable.
Migrates the Equality related methods in the new fluent paradigm.
Adds missing header files.

Clean up some useless using references.
Adds entries to the backlog
Cleans up some code and introduces a new Extension directory.
Introduces the INumericalFluentAssert interface, asserts and tests.
Introduces the Helpers and Extensions folders.