Table Storage: create TableQuery helpers

[Carl-Hugo]

Create TableQuery helpers like StartWith.

Maybe something chainable like that: query.Column("ColName").StartWith("String to check"); TBD.

See #9

[Carl-Hugo]

Ended up to be a simple extension on TableQuery:

query = query.StartWith("RowKey", "Something");

A chainable query language is another feature that may or may not come later.