Errata-tool

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* Refactor Erratum's internal `_fetch` method (code reorganization). This will
make it easier to subclass and extend functionality. New internal methods you may want to override:

* ``Erratum._cache_bug_info()``

* ``Erratum._need_rel_prep()``

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* Prepend exceptions with erratum ID if possible

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* Erratum instances have a new ``.text_only`` attribute that is ``True`` if an
advisory is text-only, and ``False`` if an advisory is a "normal" one. This
attribute is writable, and you can also set the ``text_only=True`` kwarg
during the ``Erratum`` constructor when creating an entirely new advisory.

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* Erratum instances have a new ``.embargoed`` attribute that is ``True`` if an
advisory is embargoed, and ``False`` if an advisory is not embargoed.

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* ``addBuilds()`` handles non-RPMs.

* add ``setFileInfo()``

* This release changes the signature of ``addBuilds()`` slightly. Prior to this
release, you could call it like so:

.. code-block:: python

advisory.addBuilds(['build1', 'build2'], product_version)

After this change, release must be specified as a kwarg:

.. code-block:: python

advisory.addBuilds(['build1', 'build2'], release=product_version)

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* RPM packaging fixes

* Add full MIT license text to git repository and packaging