Fix SSR with Nuxt.js

[atinux]

Hi,

To test if the component is run on client-side, we can test directly if typeof window !== 'undefined' :)

Thank you for this great component!

[staskjs]

I am not really into nuxt, but what is the problem with BROWSER_BUILD? It does not work any more?

[Ficik]

Problem with current code is that process.BROWSER_BUILD is undefined during server render and that process.BROWSER_BUILD == null is true.

Fix is either using === instead of == or check for actual dependecy of the library (window)

[xloading]

Hi @atinux !
Was this PR supposed to fix this plugin's compatibility with Nuxt?
Asking because I'm trying to use it with Nuxt right now but get the same exception as in #38 :
Unexpected token <