Update ModuleController.cs

As commented line 875 "Synchronize module is called when a module needs to indicate that the content has changed and the cache's should be refreshed." But the cache isn't refresh.
Fixed by adding the clear cache Line 886
Create doubletaptogo.js

https://dnntracker.atlassian.net/browse/DNN-3910
Create doubletaptogo.min.js

https://dnntracker.atlassian.net/browse/DNN-3910
Update Home.ascx

https://dnntracker.atlassian.net/browse/DNN-3910
Update 2-Col.ascx

https://dnntracker.atlassian.net/browse/DNN-3910
Update 3-Col-Social.ascx

https://dnntracker.atlassian.net/browse/DNN-3910
Update 3-Col.ascx

https://dnntracker.atlassian.net/browse/DNN-3910
Update 404Skin.ascx

https://dnntracker.atlassian.net/browse/DNN-3910
Update groups.ascx

https://dnntracker.atlassian.net/browse/DNN-3910
Revert "Update ModuleController.cs"

This reverts commit a3c8d2bf7c70b82be247efef3def25b752025b7b.
Update dnn.DropDownList.css

Rule ".dnnDropDownList .dt-container ul, li {" applied for all <li> elements, but must be only to <li> elements inside .dnnDropDownList .dt-container ul.
DNN-21481 Add alternate link w/ "hreflang" to sitemap.aspx for multilingual websites
DNN-4772 Remove template.resx
DNN-4543 App_GlobalResources\FileUpload.resx does not show in resource localizer
DNN-4002 add feedback message after updating a file
DNN-3933 Module creator - localization issues
DNN-4773 SQL Module style for editing is not very clear
DNN-3951 User management missing localization
 DNN-4463 SI: Remove old versions of Client Dependency files
Merge pull request #56 from vmasanas/DNN-21481

DNN-21481 Add alternate link w/ "hreflang" to sitemap.aspx for multiling...