Upgrades request and fs-extra deps

• upgrade promise polyfill

• Removes bundledDependencies from NPM publishing. This option appears to be non-portable, and breaks various OS/NPM version combinations.

• published with NPM3, to improve path nesting (#589)
• preserves paths better on install (#583)
• Adds run/exec methods (#588)

bundles the dependencies, for more robust npm installs

• minor package updates
• fixes for tmp handling

Installs phantomjs 1.9.8 binary
Uses installer script from v2.1.7
Uses github releases as the default download location

• Change the default download location to github releases, per discussion on #509 and ariya/phantomjs#13953
• If there's a global npm phantomjs-prebuilt install on linux/osx, try to use that for local installs (windows is harder for complicated windows reasons)

Remove dependency on adm-zip due to alleged GPL violations (#495)

Minor fixes to custom CA handling
Use sha-256 instead of md5 for download verification