Update stevedore base version to 1.1.0

The 1.1.0 release of stevedore fixes a packaging issue that prevents the
documentation from some projects that use stevedore from building.
See Bug #1384919 for more details.

Change-Id: I1bd09144c6606e3aa9f0264143cca98265322cc3
Merge "Update stevedore base version to 1.1.0"