(maint) Update hash syntax in uber_build polling for ruby 1.9/1.8

As we still support older rubies in our tools, we cannot yet move to the
more modern hash syntax. This commit updates the uber_build polling
argument setting to use the hash rocket instead of the newer syntax.
Merge pull request #344 from haus/maint/master/update_hash_syntax

(maint) Update hash syntax in uber_build polling for ruby 1.9/1.8