Make small fixes on developers' testing page.

Main problem was the OmeroPy path which was simply wrong.
Use canned styles following sbesson's suggestions.

also cleaned up some whitespace
merge dev_4_4 -D org -I include -E exclude: PR 245 (Add note about Java UTF-8 source in Insight.)
merge dev_4_4 -D org -I include -E exclude: PR 274 (Add information about default include/exclude filters for scc merge)
merge dev_4_4 -D org -I include -E exclude: PR 277 (Make small fixes on developers' testing page.)