BUG: Fixed exclusion list

Currently iris test coding standards will perform pep8 checks on files
contained within the build directory and then ignore the results.  This
commit removes this checking entirely and fixes a bug present in
generating the assumed directory for the iris repository from the iris
path (a problem which arises when considering softlink vs real paths).
First draft of testing guidelines
Second draft
Fix typo
ENH: Tolerance threshold for masked array aggregation

Ability added to pass missing data threshold to the aggregation class.
Minor fixes based on review and extended usage
Second iteration of changes
Merge pull request #820 from esc24/dep_history

Deprecate add_history()
Merge pull request #821 from cpelley/collapse_missdata_tol

ENH: Tolerance threshold for masked array aggregation
Fixed failing Aggregator tests on master.
Merge pull request #823 from ajdawson/fix-aggregator-tests

Fixed failing Aggregator tests on master.
Support masked arrays in broadcast_to_shape.
Added unit tests for rolling_window function.
seems to be working
updated
looks like its working
working name tests
fix test
Slight refactor
Basic TimeConstraint(hour=...) capability