comply to the es-observable spec

[danylaporte]

This will be a rewrite of asyncplify. Will need to make sure that we inline with es-observable specs

• remove pause / resume (breaking change and lost functionality) [cancelled / and reverting]
• implement the protocol
• use observer / observable nomenclature
• allow to interropt with es-obserable

Since we are simplifying the approach by removing the pause / resume functionality, we should be able to improve performance.

[danylaporte]

After removing all the pause / resume functionnality, I decide to reintegrate the feature since simplify greatly the backpressure scenario.