Adding in foreign blockchain server configuration add and remove capa…

[kennycud]

…bilities. Also adding in connection recording and connection setting capabilities.

[QuickMythril]

I have some questions about these API calls. When using addserver is that a permanent change to the list of servers, or just for the current session? It looks like some code was copied and pasted in a few places, as the response sections for the API calls say "true if removed, false if not found" which only makes sense for removeserver and not the others. Has anyone looked at the other pull request related to ElectrumX server settings which allows people to make permanent additions to their servers using the settings.json file? Perhaps a combination of these two methods could allow people to use the UI to make an API call that would update the settings file. That's something we've needed to work on as well anyway. See: #178

[kennycud]

the addserver comment "true if removed, false if not found" is wrong, it should state "true if added, false if not added", I will update these comments soon

[kennycud]

addserver changes the session only