added a Task.start method to start the future right away
Add "lossless" tags

New type is `@@@` - which is defined to be:

    type Tagged[T] = {type Tag = T}
    type @@@[+T, Tag] = Tagged[Tag]

Usage is:

    scala> Tags.MinVal.unwrap(Tags.MinVal.lossless(1) |+|
    Tags.MinVal.lossless(2))
    res0: Int = 1

    scala> Tags.MinVal.lossless(1) * Tags.MinVal.lossless(2)
    <console>:14: error: value * is not a member of
    scalaz.@@@[Int,scalaz.Tags.MinVal]
                  Tags.MinVal.lossless(1) * Tags.MinVal.lossless(2)
                                                        ^
Make `Tagged` private

Gives a tiny amount of safety - nobody should be using this directly.
LosslessTagged
Only have 2 asInstanceOf calls for lossless tags
More in-depth ScalaDoc for `\/`
Add documentation to ==>>

I had never used `==>>`, so I thought it would be nice to start looking
through its source, adding ScalaDoc comments as I went along.

This is  how far I got before I thought to check how many lines
were in the file. Adding documentation for the rest is a bit of a
daunting task, but I figured I might as well contribute what I had
already done.

:-\
add a MaybeT, this is basically just a direct translation of OptionT
changes suggested by @ceedubs :wq
Revised Monad[Task].point to evaluate lazily
Add Traverse and Zip instances for DList
Merge pull request #734 from stew/scalaz-seven

Add Traverse and Zip instances for DList
catchable on Syntaxes and ToTypeClassOps
Merge pull request #735 from tpolecat/catchable-syntax

made catchable ops importable
rename `start` to `unsafeStart`
Merge pull request #684: Task.start
Merge pull request #733 from stew/call-me-maybet

Call me maybet
Merge pull request #710 from ceedubs/docs-disjunction

More in-depth ScalaDoc for `\/`
Merge pull request #711 from ceedubs/docs-map

Add documentation to ==>>
Add an ensure method to Task similar to \/ or EitherT