Simplify circularity test in nc load rules.
Define circularity from bounds, if any.
Added tests for old+new circular logic.
bump version to v1.8.0-dev after v1.7.x branch
Merge pull request #1205 from esc24/bumpversionto1.8

bump version to v1.8.0-dev after v1.7.x branch
Up the release version
Merge pull request #1227 from bjlittle/unrelease_version

Up the release version
Added slice_over cube method
Fixed units bug when regridding with no coord_system
grib save statistic
Merge pull request #1228 from marqh/gribsavestat

grib save statistic
Merge pull request #1230 from esc24/regrid_no_cs

Fixed units bug that prevents regridding with no coord_system
Merge remote branch 'upstream/v1.7.x' into refresh

Conflicts:
	lib/iris/__init__.py
	setup.py
Review actions
Further review actions: tests improvements
Merge pull request #1229 from dkillick/slice_over

Added cube method slices_over
fixed problem with saving cubes vertical levels but missing orography
review action
Merge pull request #1236 from esc24/missing_vertical_simple

fixed problem with saving cubes vertical levels but missing orography
Merge pull request #1238 from SciTools/v1.7.x

Merging v1.7.x on to master