Fix issue with omit chainable definition not returning LoDashObjectWrapper
Add chainable definitions for _(...).pairs
Added chainable definition for _(...).reduce and aliases.
Added chainable definitions for _(...).pluck
Added chainable definition for _(...).uniq and aliases
Added TResult generic to chainable _(...).pluck methods

This is needed because there is no way to cast the output in the middle of the chain.

This is not be done on _.pluck() methods because T cannot be inferred.  In other words, this:

    <number>_.pluck(objectArray, 'id');

or this:

    var id: number = _.pluck(objectArray, 'id');

is cleaner than this:

    _.pluck<IMyObjectInterface, number>(objectArray, 'id');
Added chainable definitions for _(...).reject
Added chainable definitions for _(...).sortBy
Added chainable definitions for _(...).where
Added chainable definitions for _(...).first and aliases
Add chainable definitions for _(...).keys
Add chainable definitions for _(...).forEach and aliases when passing an non-dictionary object.