v0.10.0

Updates with new features and changes from Puppeteer 1.7.

• Add waitForRequest and waitForResponse functions (#67)
• Add BrowserContext.pages method (#69)
• Add "preferCSSPageSize" to Page.pdfOptions (#70)
• Fix Page.viewport and Page.emulate (#71)
  • Make all fields in viewport optional except for width and height.
  • Construct the viewport using bs.deriving abstract.
  • Remove unnecessary unit argument to Page.viewport().
  • Rename Page.emulateOption to emulateOptions.
• Add defaultViewport options and handle null viewports (#73)
  • Note: Page.viewport() now may return null
  • Make Viewport a top level module
• Add options arg to Puppeteer.defaultArgs (0fb495d)