Fixes #52
Fixes #52

The current implementation calculates:
\Phi\left(\frac{f(x^+) - \mu(x) + \Psi}{\sigma(x)} \right) \\
= P(f(x) \leq f(x^+) + \Psi) \\
= P(f(x) - \Psi \leq f(x^+))

Where Psi is the jitter term.

This commit fixes it so that it correctly calculates P(f(x) + \Psi \leq f(x^+))

SheffieldML/GPyOpt