Increase test coverage

[Reewr]

Only 12% left to cover before we have it all. I don't think I'll ever get 100%. But here is what is missing according to the latest coveralls:

index.js

• create - Reject error

lib/phantom.js

• createPage() - Reject error on createPage
• getCookie() - Retrieve cookie that does not exist while other cookies exist
• exit() - Run function after phantom has exited.
• exit() - Reject error on exit
• on() - Not tested at all

lib/webpage.js

• printDeprecatedArrowFn() - Run with silencing
• setFn() - Run with using arrow function
• set() - Run with using arrow function
• evaluate() - Run with using arrow function
• waitForSelector() - Run without specifying timeout
• close() - Run function afer page has closed
• close() - Reject error on close
• evaluateAsync() - Run with using arrow function
• getPage() - not tested at all due to Page.getPage doesn't return Page #5
• openUrl() - No idea how this works. Gotta find some information about it
• sendEvent() - Not tested.
• stop() - No idea how to test this due to the async nature of things.
• switchToFocusedFrame() - No idea how to test this either
• switchToFrame() - or this
• switchToMainFrame() - or this
• switchToParentFrame() - or this
• uploadFile() - Test that file is uploaded
• clearMemoryCache() - Run function
• waitForLoad() - Make sure to test where the load time is longer
• renderHtml() - Test this function where status of open() returns failure
• onFilePicker() - Test handler

lib/utils.js

• mkpath() - with mode set
• tmp.file() - with no options
• tmp.dir() - with no options