removes unneeded lock on master controller factory - must have been left over from some v5 stuff for some reason :( this will speed things up a bit!
Microsoft.Net.Http required a reinstall command for the UI project as noted by it's persisted 'requiresReinstall' attribute in the packages.config - also ensures that ALL of the WebApi DLLs are copied local
Merge remote-tracking branch 'origin/6.2.2' into 7.1.5

Conflicts:
	src/Umbraco.Web.UI/Umbraco.Web.UI.csproj
	src/Umbraco.Web.UI/packages.config
updates proj references to have SpecificVersion set to false for libs
updates proj references to have SpecificVersion set to false
Merge remote-tracking branch 'origin/6.2.2' into 7.1.5

Conflicts:
	src/Umbraco.Web.UI/Umbraco.Web.UI.csproj
	src/Umbraco.Web/Umbraco.Web.csproj
Fixes up back office search, U4-5048, U4-5021, U4-5167, U4-5194
Merge branch '7.1.5' of https://github.com/umbraco/Umbraco-CMS into 7.1.5