fix normalizing of homeserver

[ashfame]

PR fixes the normalizing approach towards homeserver.

Before this PR, function wasn't able to normalize synapse.dev:8008 homeserver correctly.

Here is the output prior to this PR:

"synapse.dev" -> "https://synapse.dev"
"synapse.dev:8008" -> "null"
"https://matrix.org" -> "https://matrix.org"
"https://matrix.org:8080" -> "https://matrix.org:8080"
"http:// invalid" -> "https://http"

With the changes in PR, the output is as follows:

"synapse.dev" -> "https://synapse.dev"
"synapse.dev:8008" -> "https://synapse.dev:8008"
"https://matrix.org" -> "https://matrix.org"
"https://matrix.org:8080" -> "https://matrix.org:8080"
"http:// invalid" -> ""

Signed-off-by: Ashish Kumar ashfame@users.noreply.github.com