Support Microsoft IE11

[benzitohhh]

Hi there,

Nivo is amazing, nice one for all the hard work.

But unfortunately it does not currently work with IE11.

Specifically, curve.js has a call to str.endsWith, which IE11 does not support.

Please could this fix be added:
#231

Or perhaps it could be fixed in your build?

Thanks,
Ben

[li4man0v]

i'd recommend using external polyfills rather than adding them to the library

[plouc]

@benzitohhh, I agree with @reanimatter, I've answered on your MR #231.

[benzitohhh]

@plouc @reanimatter ok cool all good - thanks for looking at this