Merge pull request #217 from gforcada/custom-headers-on-tests

Tip for adding custom headers on tests
=Added instructions to generate security headers and avoid issues with default virtualhost on apache.
Added latest link and Windows missing note
Update installation.rst
RST fixes
Merge branch 'master' of github.com:collective/collective.developermanual
Merge pull request #218 from xiru/master

=Added instructions to generate security headers and avoid issues with d...
Merge branch 'master' of github.com:collective/collective.developermanual
Clean up install instructions
Clean up warnings and errors
add note about Riv vim plugin for rst
Add warning against plone ports and packages.
Merge branch 'master' of github.com:collective/collective.developermanual
Clean up obsolete instructions.
Update Plone version
Added Contributors box
Add Ubuntu version
Merge branch 'master' of github.com:collective/collective.developermanual
Merge branch 'master' of github.com:collective/collective.developermanual
Remove obsolete information; edit for clarity.