reset pluggableTransports settings after switching to a new provider if the new one doesn't support PT

add pluggable transports demo as separate entry to Bitmask's onboarding provider overview, ship provider cert and provider json for certificate pinning and a better initial provider description

fix error handling for failing fetch of eip-service.json in production flavor and minor refactorings

[New Feature] Option for excluding apps from VPN

See merge request !93