Merge pull request #24 from DrMarcII/master

General cleanup of WebDriver.
Update README.md
add missing content-type to HTTP request
Merge pull request #25 from goderbauer/patch-1

add missing content-type to HTTP request
Update web_driver.dart

remove => for void functions that call another function with return value. If the called function actually returns something this fails with "Caught type '_LinkedHashMap' is not a subtype of type 'void' of 'function result'." because the void function cannot return what the called function returned.
Merge pull request #27 from goderbauer/patch-2

Update web_driver.dart
Update pubspec.yaml
Update version numbers.
Merge branch 'master' of https://github.com/google/dart-sync-webdriver

Conflicts:
	pubspec.yaml