Checkbox to Enable/Disable Network Features

[andrewd18]

I would like to see a new settings option by which I can enable or disable network features, so PyFA isn't continually trying to access websites that are blocked by my company's firewall (namely eve-central).

[DarkFenX]

Pyfa uses network for 3 things atm:

1. Update checks
2. Price updating
3. API character sheet fetches

I think best solution UI-wise would be to create 'parent' tick 'allow networking features' and have 3 sub-ticks (which are grayed out if parent tick is disabled). Update networking activity can be suppressed already, so we need implement something similar for price and API stuff

[blitzmann]

Would it be better to create a network service? All network requests go through this (instead of individual calls), and this way we can bake the proxy / disabling stuff into the service.

[blitzmann]

Finally got a proxy working, so I'll be starting to migrate all network calls to a new network service.

There are two uncertainties as of right now:

• Price checking is done on an EOS level. We shouldn't import services (networking) into EOS. At the moment the EOS Price object simply represent the value in the database and is used to update it. I'm sure we can make a Pricing service that does this.
• EVE API will have to be reworked slightly for this, as it has it's own proxy support. I haven't looked into this beyond that tho. However, when testing out my proxy implementation, I noticed that while prcing updates worked well, API update crashed pyfa with no output in terminal. My proxy logfile shows a request for Request: api.eveonline.com/ so it's possible that the URL is not being assembled correctly and the API hangs due to incorrect API issues.

While working on this, I will also try to address #35 if I can. We'll see...