Fix EPERM error on Windows with A/V software

On Windows machines with anti-virus software, renaming immediately after extracting fails due to an EPERM error. This is caused by the A/V locking up files while it is scanning them, thus disabling renaming. The solution is to re-try renaming until the EPERM error stops occurring, which happens after the A/V stops scanning the files, as described here: https://github.com/isaacs/npm/commit/beeb7fd82e3cc543a9911fe87ec096f8eed29e7a

Fixes https://github.com/Obvious/phantomjs/issues/19