Merge pull request #12 from zachconrad/master

Adding WebDriver specific matchers
Merge pull request #13 from zachconrad/master

ListOf() is no longer necessary
Merge pull request #14 from zachconrad/master

Adding ability for page loader to inject functions.
Update pubspec.yaml

Update version number.

Update dependency version numbers to match recommendations.
Adding toString() method to by, fixing 'Instance of By' being the description for everything