Optimized Dockerfiles to reduce number of layers

[brunoborges]

use one single ENV and one single RUN instead, to reduce number of layers. Use COPY instead of ADD for files you don't intend to extract, and as many files as you want, if they will end up being in the same directory.

[AdamBien]

I usually do not chain command due the readibility. However: sometimes it is handy to execute multiple commands at the same time (like start and configure GF :-)). I removed most of the RUN commands - I forgot to remove them. COPY vs. ADD is a good one.