Reduce number of evaluated queries.

* Replace "foo.count() == 0" with "not foo.exists()" in python files
* Replace "foo.count() > 0" with "foo.exists()" in python files
* Replace "{% if foo.count %}{% for bar in foo %}" with
  "{% if foo %}{% for bar in foo %}"
* Use 'with' template tag in templates
* Add myself to AUTHORS list
Reduce number of evaluated queries.

* Properly close with tag.
* Properly check for band existance
Reduce number of evaluated queries.

Use 'for..empty' templatetag
Don't use |length filter if not reqired
Mark a few forgotten strings translatable

* Postcode validation message
* Basket price change warning
* "No reviews available" in template

Fixes #1050
Fix .travis.yml for Django 1.6

This should make Travis CI work again.
Merge pull request #1056 from piotrjakimiak/reduce_sql_queries

Reduce query count
New lib to get query counts for test suite

nose-django-querycount gives individual and total query counts. This is
helpful to double-check changes that claim to affect query count
(e.g. #1056).
Total query count gives a quick overview, and diff'ing the output for
two different branches works well.
Move timepicker JS load to dashboard's layout.html

@mbertheau correctly suggested as there's dashboard-global
initialisation going on in dashboard.js, loading the timepicker addon
should be global as well. That's more consistent with how we handle
other dashboard plugins as well.
Merge pull request #992 from tangentlabs/issue/992/datetimepicker

Fix datetime picker in dashboard
Remove ancient import

Not sure how this survived this long.
Correct flash message when saving a variant product
Merge branch 'partner-user-customizing' into machtfit

* branch partner-user-customizing:
  Remove now unused method Product.is_user_a_partner_user
  Extract ordering the queryset into a method
  Filter out products the the user isn't allowed to edit in one place
  Extract method that applies the dashboard product list search query

https://github.com/tangentlabs/django-oscar/pull/1059
Merge branch 'easily-add-new-formset-to-product-update-page' into machtfit

* branch easily-add-new-formset-to-product-update-page:
  Provide a hook for cross-form validation
  Make it trivially easy to add more formsets to the product update page
  Unify __init__ method signature of formset classes
  customize FormSet class after calling inlineformset_factory
  Whitespace, Formatting, PEP8

https://github.com/tangentlabs/django-oscar/pull/1022

merge dashboard-fix-custom-permissions
https://github.com/tangentlabs/django-oscar/issues/993
https://github.com/tangentlabs/django-oscar/pull/1034

Conflicts:
	oscar/apps/dashboard/catalogue/views.py
Merge branch 'partials-product-template-block' into machtfit

* branch partials-product-template-block:
  Add template block for easier customization

https://github.com/tangentlabs/django-oscar/pull/1051
Merge branch 'passwordreset-singleobjectmixin' into machtfit

* branch passwordreset-singleobjectmixin:
  Make it easy to restrict the users you can use this form with.

https://github.com/tangentlabs/django-oscar/pull/1052
Merge branch 'bulkeditmixin-use-get-queryset' into machtfit

* branch bulkeditmixin-use-get-queryset:
  Retrieve objects from get_queryset instead of default manager.
  Don't hide base class get_queryset.
  Whitespace

https://github.com/tangentlabs/django-oscar/pull/1065