chore: Bump version to icehouse-2 dev

This patch makes our version more specific in preparation for doing
interim project releases for each OpenStack milestone. The OS wiki
does not specify what to do about "development" versions, so I
decided to follow the standard Python convention.

Change-Id: Icae5b7abbb33969a60b3a517b9a016016180d0f5
Merge "chore: Bump version to icehouse-2 dev"