Minor changes to wording in theorems 1 and 3

Changes the phrasing slightly, but should not change the content or meaning
of any statements in the paper.
Remove weak-stationarity requirement in theorem 1

Under the null, the mean is zero; so assuming covariance stationarity is
just a restriction on the variances.  That restriction isn't necessary for
the CLT to hold, so I'm removing it.
Add requirement of constant mean to theorem 3

Without a constant mean, the OOS bootstrap used in Theorem 3 is not valid.
So I'm adding the assumption.