Use forwardRef rather than custom forwardedRef prop

[cpmsmith]

Closes #199.

As discussed in the issue, this is a breaking change.

This branch is based on #502, which can be merged separately.

[robmadole]

@cpmsmith ok this looks great. So now I'm thinking about documentation.

Since forwardRef was introduced in React 16.3.0 it seems like we can create a little table that describes what version of react-fontawesome you need based on the version of React. Something like this?

---

react-fontawesome now supports forwardRef for version 0.2.x or above. This was a breaking change so if you are using React older than version 16.3.0 choose the 0.1.x version of this component.

Compatibility

React version	react-fontawesome version
< 16.3.0	0.1.x
>= 16.3.0	0.2.x

[cpmsmith]

@robmadole Yeah, sounds great to me!

[cpmsmith]

@robmadole Does this need anything more from me to be merged/released? I looked around for the website source, and didn't find anything—I assume it's private to you folks. Or did you mean we should put that table in this repo's readme?

[robmadole]

@cpmsmith no nothing more from you! I've just got a stack of stuff I'm workin through currently and I haven't made it down to this. I'll update the docs both in this repos README.md and on the fontawesome.com site. You are correct though the source code for our site is private so you won't find that anywhere. I hopefully can get to releasing this next week; or that's my goal.

[robmadole]

ok @cpmsmith I've got 0.2.0 released. I've also updated the README's on each branch to mention the difference between versions 0.1 and 0.2.

Thanks again for this work. Really appreciate it.

[BasudevBharatBhushan]

can we trigger click() event on fontawesome icons?