Add option for Solr pod affinity

[timterle]

Is your feature request related to a problem? Please describe.
If there are three nodes and SolrCloud "replicas" is set to 3, then all 3 Solr jvms are put on the same node. For performance and HA reasons it'd be preferred to spread out the Solr jvms.

Describe the solution you'd like
It should be possible to configure pod affinity so that the Solr jvms are spread on all available nodes. The zookeeper operator does this.

[HoustonPutman]

Hey @timterle , @sepulworld already has a PR in to add this functionality! Check out #35 . It's almost done but I think he might have had some more work to do on it before we can merge it.

[timterle]

That sounds great @HoustonPutman and @sepulworld! I'll close this then.

[sepulworld]

Yes, sorry I was side tracked on some other things last couple weeks. Will get back to #35 soon!