API Endpoint doesn't check for trailing slash

[WhoSoup]

Client.FactomdRequest/WalletdRequest just tacks on "/v2" without checking to see if the provided url already has a trailing slash.

This works:

	cli := &factom.Client{FactomdServer: "https://api.factomd.net"}
	h := new(factom.Heights)
	fmt.Println(h.Get(cli))

This doesn't work:

	cli := &factom.Client{FactomdServer: "https://api.factomd.net/"}
	h := new(factom.Heights)
	fmt.Println(h.Get(cli))

[AdamSLevy]

The proper way to handle this would be to use net/url and call url.Parse() and check for the URL{}.Path string.

On the other hand, we could omit appending the "v2" string all together. Which I like better actually. This requires the user of this package to know the exact URL.

For applications where the user shouldn't have to be more strict, the above approach can be taken before passing the url strings to this package.

[AdamSLevy]

It is now entirely up to client to have the request URL correct. The trailing /v2 is no longer appended and clients must add this path to their URLs if needed for the servers they are connecting to.