Try to optimize page load time with Boot-reload

[Deraen]

Boot-reload client currently depends on e.g goog.net.jsloader and goog.net.WebSocket and in total the Closure library dependencies of the client add about 90 JS files to the compiler output. This can add several seconds to the page load time.

• Jsloader is probably required for hot reloads (it is used by Figwheel also)
• goog.net.WebSocket / goog.events doesn't currently provide anything important over bare WebSocket, but it has support for automatic reconnecting exponential back-off which could be useful.
• Several other Closure modules are also used

Slow page load might partly be caused from using Chrome "Disable cache". It would be good to check that everyhing works with cache enabled.