Support for AspNet_Merge

[Kralizek]

First of all, this is a great package! thank you so much!

It would be perfect if we could also add support for AspNet_Merge.

This would create a single assembly to be added in the bin folder.

ref: https://msdn.microsoft.com/en-us/library/bb397866.aspx

[DavidDeSloovere]

Single assembly would make the site even faster.
The AspNetCompiler tasks that is currently used doesn't support merging into a single assembly.
https://msdn.microsoft.com/en-us/library/ms164291.aspx
So this would have to be done by calling into the commandline aspnet_merge.exe as mentioned.