Decrease the amount of RAM required to run the containers

[aborroy]

From a living execution, following stats are obtained:

CONTAINER ID   NAME                 CPU %     MEM USAGE / LIMIT     
25c7cd77650f   alfresco             51.52%    1.927GiB / 2.93GiB    
dbaf4968f224   solr6                13.53%    651.2MiB / 1.953GiB   
5e091b2d8114   transform-core-aio   0.24%     718.3MiB / 2GiB       
6144935b31d1   activemq             0.63%     221.2MiB / 1GiB       
6bdb000b1ba3   postgres             3.99%     110MiB / 1.828GiB

This makes a memory limit of 11 GB, but following services seems to be oversized: solr6, activemq, postgres.

Decreasing the memory reservation for this containers could help people to run the Extension.

[aborroy]

Proposed memory limits:

• alfresco: 3 GB
• solr6: 1 GB
• transform-core-aio: 1,5 GB
• activemq: 768 MB
• postgres: 768 MB

This will give a total of 7 GB RAM as memory limit.