[DRE-maint] ruby-sidetiq is marked for autoremoval from testing

[Debian testing autoremoval watch]

ruby-sidetiq 0.6.3-4 is marked for autoremoval from testing on 2015-09-15

It (build-)depends on packages with these RC bugs:
794359: ruby-redis-namespace: FTBFS: port tests to rspec 3 for updating to 1.5.2
795677: ruby-hitimes: Non-determinstic FTBFS due to unreliable timing benchmarks in tests