Tweak README text

[firebase-release] Updated ReactFire to 1.0.0

[firebase-release] Updated ReactFire to 0.7.0

[firebase-release] Updated ReactFire to 0.6.0

[firebase-release] Updated ReactFire to 0.5.1

[firebase-release] Updated ReactFire to 0.5.0

[firebase-release] Updated ReactFire to 0.4.0

[firebase-release] Updated ReactFire to 0.3.0

[firebase-release] Updated ReactFire to 0.2.0

Got tests running in PhantomJS by adding shim for it