Added command to open caniuse.com for feature.

[nchutchind]

Used the same as the default behavior, but with a different shortcut will open the browser to caniuse.com/selectedWord.

[coveralls]

Coverage remained the same at 100.0% when pulling 00eaea8 on nchutchind:master into 8fb16ad on akamud:master.

[akamud]

Hi, thank you for sending this, I looked at the code and I see that you are using the selected word to send to CanIUse, they use keywords for most of the rules, so just sending the selected word won't work for many rules.

To address this I started using a "mapping" file so it always send the correct keyword to CanIUse. You can see it in use in here.

You should change your code to use this mapping file before calling caniuse.com

[yangg]

I think click the status bar to open caniuse.com is also a good feature.