BLD: Updates to conda build files. Now builds on windows.
MAINT: Re-enable algorithms which omit initialize method.

Though defining the `initialize` method may end up being explicitly
required, in the meantime prevent existing algorithms from crashing
by providing a noop function when `initialize` is not defined.
STY: Indentation fix in stddev.
BUG: Check required fields for stdev transform.

Move the assert method to the EventWindow subclass, to be
consistent with other transforms; also, add the check to
`handle_add`.
BUG: Prevent crash in vwap transform due to non-existent member.

The WrongDataForTransform was referencing a `self.fields` member,
which did not exist.

Add a self.fields member set to `price` and `volume` and use
it to iterate over during the check.
MAINT: Names were reversed from their actual values