fix rhts_partitions syntax error with Jinja 2.6

Apparently the 'set' statement accepts an empty RHS in Jinja 2.2 (RHEL6)
but not in Jinja 2.6 (Fedora).

    Traceback (most recent call last):
      File "/usr/lib/python2.6/site-packages/bkr/server/tools/beakerd.py", line 549, in scheduled_recipes
        recipe.provision()
      File "/usr/lib/python2.6/site-packages/bkr/server/model.py", line 5188, in provision
        recipe=self, ks_appends=ks_appends)
      File "/usr/lib/python2.6/site-packages/bkr/server/kickstart.py", line 215, in generate_kickstart
        result = template.render(context)
      File "/usr/lib/python2.6/site-packages/Jinja2-2.6-py2.6.egg/jinja2/environment.py", line 894, in render
        return self.environment.handle_exception(exc_info, True)
      File "/usr/lib/python2.6/site-packages/bkr/server/snippets/rhts_partitions", line 55, in template
        {% set myfstype = %}
    TemplateSyntaxError: Expected an expression, got 'end of statement block'

Change-Id: I1106280a53ddb0a0ab113d2933ab6f9a56140252
fix a bunch of Unicode type warnings

Change-Id: I97efd3e1040179ba0c1106dda0e211b2bd2ed00b
two-argument .join() is not accepted in sqlalchemy 0.7

    Traceback (most recent call last):
      File "src/bkr/inttest/server/test_kickstart.py", line 1020, in test_beaker_url
        ''', self.system)
      File "src/bkr/inttest/server/test_kickstart.py", line 272, in provision_recipe
        recipe.provision()
      File "../Server/bkr/server/model.py", line 5118, in provision
        .combined_with(self.generated_install_options())\
      File "../Server/bkr/server/model.py", line 4699, in generated_install_options
        'packages': ':'.join(p.package for p in self.packages),
      File "../Server/bkr/server/model.py", line 4805, in _get_packages
        .select_from(RecipeTask).join(Task, Task.required)
      File "/usr/lib64/python2.7/site-packages/sqlalchemy/orm/query.py", line 1638, in join
        from_joinpoint=from_joinpoint)
      File "<string>", line 1, in <lambda>
      File "/usr/lib64/python2.7/site-packages/sqlalchemy/orm/query.py", line 50, in generate
        fn(self, *args[1:], **kw)
      File "/usr/lib64/python2.7/site-packages/sqlalchemy/orm/query.py", line 1767, in _join
        outerjoin, create_aliases, prop)
      File "/usr/lib64/python2.7/site-packages/sqlalchemy/orm/query.py", line 1791, in _join_left_to_right
        prop)
      File "/usr/lib64/python2.7/site-packages/sqlalchemy/orm/query.py", line 1820, in _prepare_right_side
        "the right side of join condition %s" % (right, onclause)
    InvalidRequestError: Join target <class 'bkr.server.model.Task'> does not correspond to the right side of join condition Task.required

Change-Id: I750418194fee6f685e31e4f4c8f0ac010ca469d1
make a note about why recipes only expire when the entire recipe set is expired

Since this question comes up regularly I thought it would be good to
make a note of it here.

Change-Id: I58680996414863769a5acaf69dbcfcee54254e08
Merge changes I58680996,I75041819,I97efd3e1,I1106280a into develop

* changes:
  make a note about why recipes only expire when the entire recipe set is expired
  two-argument .join() is not accepted in sqlalchemy 0.7
  fix a bunch of Unicode type warnings
  fix rhts_partitions syntax error with Jinja 2.6