Add stable nginx.

Also add specific module for hexaglobe.
Fix comment in softwaretype about state of falsy parameters.
Add statement about complete uselessness of this download recipe.
Add helper method to set "location" parameter in librecipe.

Set to buildout['buildout']['parts-directory'] + name.
Used in 50% of the recipes.
Add download helper function in librecipe.
Update wrapper recipe to make it simpler and more dev-friendly.
Add configurationfile recipe.
Update pinned egg versions in LAMP stack.
Add lamp-generic SR.
Add temporary request-edge recipe
Add publishsection recipe.
Add 'edge' support for lamp-generic with 'edge' software_type.
Add SLA to request.edge
Don't send frontend url.
Add hexaglobe-watermarking Software Release.

To be separated into smaller commits.
hexaglobe-watermarking: follow recent improvements in recipe.

To be squashed.