Remove properties= from Blob and Bucket constructors

[dhermes]

NOTE: Has #759 as a diffbase.

This is an implementation detail intended to make internal code have an easier time constructing entities, but never had a story for end-users.

The only real changes are effectively:

-            yield Bucket(properties=item, connection=self._ctor_connection)
+            name = item.get('name')
+            bucket = Bucket(name, connection=self._ctor_connection)
+            bucket._properties = item
+            yield bucket

For test conveniences, I've allowed _makeOne() to delegate the properties= keyword in the way it used to be used in the actual constructors.

[coveralls]

Coverage remained the same at 100.0% when pulling 9cd15a6 on dhermes:remove-properties-from-constructor into d34a15e on GoogleCloudPlatform:master.

[coveralls]

Coverage remained the same at 100.0% when pulling 9cd15a6 on dhermes:remove-properties-from-constructor into d34a15e on GoogleCloudPlatform:master.

[tseaver]

Changes relative to #759 LGTM.

[coveralls]

Coverage remained the same at 100.0% when pulling 44e5b74 on dhermes:remove-properties-from-constructor into 3906245 on GoogleCloudPlatform:master.

[dhermes]

@tseaver I peeled off the last two commits to separate from #759. Let me know if you're not cool with the merge.