Stop using Twisted Reactor which is the main event loop of Twisted
Do not print private key to console
Merge pull request #737 from yagoulas/drop-reactor

Drop reactor
Drop all references to twisted.
Drop Twisted from requirements.
Upgrade tornado to version 4.0.2.
Remove logging of settings
Merge pull request #751 from dionyziz/hide_private_key

Do not print private key to console
Merge pull request #753 from Renelvon/bump_tornado

Upgrade tornado to version 4.0.2.
Merge pull request #752 from Renelvon/drop_twisted

Drop twisted from requirements
Abstract the Elliptic Curve used; setup initial testsuite.

* Introduce crypto_util.BTC_CURVE as the curve's name. Replace any
  magic strings in the codebase with crypto_util.BTC_CURVE.
* Invoke pyelliptic.OpenSSL to get curve ID
* Abstract the key length.
Abstract and test public and private key processing.

* pubkey_to_pyelliptic now returns key in bin format.
* Replace hexToPubkey with pubkey_to_pyelliptic.
Create and test a Cryptor class to abstract pyelliptic.

* Replace makePubCryptor, makePrivCryptor and ec.ECC with Cryptor.
* Provide the ECC key getters; do not keep the keys in Cryptor class.
* Purge pyelliptic imports outside crypto_util.
* Purge most references to _myself; let's not be self-centered.