Changed JavaScript Tracking Code generation to use "//", instead of verifying whether the site is using "https", or not, and generating a corresponding URL.

"//" has been part of the RFC for well over 18 years. It has been confirmed to work in all major browsers (Firefox, Chrome, IE, Opera).

References:
- RFC 1808 Section 4: http://www.ietf.org/rfc/rfc1808.txt
- RFC 3986 Section 5.2: http://www.ietf.org/rfc/rfc3986.txt
- Stack Overflow QA 1: http://stackoverflow.com/q/4659345/238722
- Stack Overflow QA 2: http://stackoverflow.com/q/6785442/238722
First attempt at fixing failing tests.
Merge branch 'master' of https://github.com/piwik/piwik
Missed one correction on the failing tests.
Added the protocol-agnostic URL format to the Tracker's fallback image.
Merge pull request #344 from Irrational86/master

Changed JavaScript Tracking Code generation to use "//"