Major memory leaks

[firasdib]

You're adding events with specific flags here:

https://github.com/chrisbateman/impetus/blob/master/src/Impetus.js#L194-L198

They need to be removed with the same flags here:

https://github.com/chrisbateman/impetus/blob/master/src/Impetus.js#L238-L242

You must also ensure these events are removed when destroying the instance.

This is a huge issue for us right now and its causing all touch move events to be swallowed up by this, blocking our app.

[firasdib]

See #41

[firasdib]

Also this:

[Intervention] Ignored attempt to cancel a touchmove event with cancelable=false, for example because scrolling is in progress and cannot be interrupted.

[weotch]

@firasdib with the merging of #41, this can be closed now, right?