tealdbg - configuration option

https://github.com/algorand/go-algorand/blob/master/cmd/tealdbg/README.md describes how to modify the algod to turn on the Web debugger. This should really be a configuration option, like EnableDeveloperAPI, rather than something where you modify the code to turn it on. Moreover, the instructions are wrong, because you need to add "os" to the import list as well.

This is what I'm using for now, but it would be better to really update config.go: https://github.com/jeapostrophe/go-algorand/commit/114a516f04bed34cec18fd453e6754b6ea8beb53