Add class name prefixes to fix potential style leaks

[rbrtsmith]

As it currently stands we are not prefixing our classNames e.g. we have .sidebar
which means consumers CSS is likely to leak into the timeline.

I suggest we prefix all our classNames with rt- to avoid this.

[willbamford]

We have .react-timelines wrapper which adds some level of protection but agree there is still likely to be some leakage.

Something like .rt or .rtl would help at the expense of readability / noise in the code-base. Would also not guarantee working okay e.g. users can just style p directly and there isn't much we can do about this.