Emphasize omero_prefix over omero_home
Add new page for omero_home recommendations
Cross-reference the new omero_home page
clarifying 'OMERO_PREFIX' in install doc
Style & proofing edits & clarifying OMERO_PREFIX
Fix rst role name typo
Fix spelling
Merge pull request #667 from zeb/doc-omero-home-dev-5-0

Add details for omero_home usage