Drop Extension==dev requirement

pip doesn't install links included in the description of projects
anymore. Therefore ==dev install doesn't work anymore.

docs/extensiondev.rst

@@ -366,7 +366,7 @@ extension to be approved you have to follow these guidelines:
    or ``python setup.py test``.  For test suites invoked with ``make
    test`` the extension has to ensure that all dependencies for the test
    are installed automatically.  If tests are invoked with ``python setup.py
-    test``, test dependencies can be specified in the :file:`setup.py` file.  The
+   test``, test dependencies can be specified in the `setup.py` file.  The
    test suite also has to be part of the distribution.
 3. APIs of approved extensions will be checked for the following
    characteristics:
@@ -380,17 +380,13 @@ extension to be approved you have to follow these guidelines:
 5. The naming scheme for official extensions is *Flask-ExtensionName* or
    *ExtensionName-Flask*.
 6. Approved extensions must define all their dependencies in the
-    :file:`setup.py` file unless a dependency cannot be met because it is not
+   `setup.py` file unless a dependency cannot be met because it is not
    available on PyPI.
 7. The extension must have documentation that uses one of the two Flask
    themes for Sphinx documentation.
-8.  The setup.py description (and thus the PyPI description) has to
+8. The ``zip_safe`` flag in the setup script must be set to ``False``,
-    link to the documentation, website (if there is one) and there
-    must be a link to automatically install the development version
-    (``PackageName==dev``).
-9.  The ``zip_safe`` flag in the setup script must be set to ``False``,
    even if the extension would be safe for zipping.
-10. An extension currently has to support Python 2.6 as well as
+9. An extension currently has to support Python 2.6 as well as
    Python 2.7