Address static class guard (#166)

As static class cannot be constructored, to verify its static members,
the null instance should be passed.
Except instance methods to veirfy static type

The GetMethods method for static class returns the instance methods of
object as ToString, GetHashCode, and GetType. This commit addressed to
except the instance methods when Veirfy(Type) method is called with
static class.
Refactoring - extract the CreateMethod method.
Address trivial matters in GuardClauseAssertion

- Removed unused using drective.
- Addressed typos.
- Addressed 'this.' prefix.
Incremented patch version,

in order to indicate a bug fix. This resolves #166
(https://github.com/AutoFixture/AutoFixture/issues/166).