Connection string is now dynamically loaded from elmah configuration

I need to log the elmah errors to the same database my application uses, I found that I would have to duplicate my already existing connection string, or rename mine to ElmahConnection, in order for the migrations to work.

I thought about simply modifying the ElmahContext.Initialize() method to take a connection string, but I noticed that you recently took that out. As I gave it more thought, I realized that we already have everything we need because the elmah/errorLog config section lets us specify a connection string. Reading the already dynamic config value gives us the flexibility to use a separate database for our elmah logs, or use an already existing connection with no duplication of configuration information.