Adjustments to pep8
Merge pull request #1 from noisy/bug_1889

Adjustments to pep8
New tests for utils: mean, interval, seconds_since_midnight, group_by_weekday.
New tests for views: mean_time_weekday_view, presence_weekday_view
Corrections after review.
Patched to bildout
Merge pull request #2 from noisy/bug_1892

Bug 1892 - Zwiększenie pokrycia testami