Add tasks to taza to download drivers and add them to the path

[orieken]

seems like all the drivers are getting split out. would it be a good idea to add rake tasks that will go get and install the driver you want to use. we could just add them to a tools dir in the project root and make sure they get added to the path so they are available to use

[lunks]

What drivers? It seems it's best to have them available as a service i.e. chromedriver via brew than to download them on each project. My 2c. :)

[tnypxl]

This is a gem that does exactly this: https://github.com/titusfortner/webdrivers

#43 Adds this gem as a dependency and should close this issue when merged.