[WIP] Upgrade dependencies for Beta 4.0

### Motivation
This is the monthly dependency check and update.

### Packages updated
* `IPy`
* `Pillow`
* `pyzmq`
* `qrcode`
* `requests`

See the commit messages for details.

### Packages kept back
* `bitcoin`: Though the latest version (`1.1.19`) delivers important fixes and improved Python 3 compatibility, it fails to install correctly under `pip`. So happens with all versions greater than `1.1.16`. Our current version is `1.1.15` and there is little reason to update to `1.1.16` right now. We should revisit this issue when a newer version of `bitcoin` fixes the installation problems.