Merge pull request #807 from superdesk/master

Update from master.
LB-1881 - As a user, I want to generate HTML with several different themes
Merge pull request #809 from ioanpocol/devel

LB-1881 - As a user, I want to generate HTML with several different them...
LB-1881 Multiple SEO configs
LB-1881 Multiple SEO configs

Some UI changes
Merge pull request #810 from vladnicoara/seo-themes

LB-1881 Multiple Seo themes
LB-1893 - Change the name of the generated file
Merge pull request #811 from ioanpocol/devel

LB-1893 - Change the name of the generated file
LB-1893 : Change the name of the generated file

Updated the file name when the theme is changed
Merge pull request #812 from ioanpocol/devel

LB-1893 : Change the name of the generated file
LB-1893 : Change the name of the generated file
Merge pull request #813 from ioanpocol/devel

LB-1893 : Change the name of the generated file
LB-1893 : Change the name of the generated file
Merge pull request #814 from ioanpocol/devel

LB-1893 : Change the name of the generated file
LB-1881 Multiple SEO configs

Some UI changes
Merge pull request #815 from vladnicoara/seo-themes

LB-1881 Multiple SEO configs
LB-1892 : [RP] Set "number of items" in SEO settings to 20 by default
Merge pull request #816 from ioanpocol/devel

LB-1892 : [RP] Set "number of items" in SEO settings to 20 by default
LB-1881 Multiple SEO configs

Some UI changes
Merge pull request #818 from vladnicoara/seo-themes

LB-1881 Multiple SEO configs