Add support for podtemplatespec / container in the Integration CRD

[lburgazzoli]

Sometime you need to add very specific configurations to the PODs created by camel-k so instead of trying to cover all the aspect through the cli and custom config, wonder if our source should have some options to configure the containers, like using podtemplatespec as for the deployment resource

[nicolaferraro]

That would simplify also #1122. And in general cover non-standard cases.

[mmelko]

I can look at this.