Dramatically Increased HTTP Timeout

python-bitcoinlib’s default is 30 seconds (and Bitcoin Core is sometimes
very slow); it’s now one hour, and set in `config.py`.

However, this value doesn’t have any effect with python-bitcoinlib
before v0.3.0.

Solves #554.

Conflicts:
	lib/backend.py
Bump Required Version of python-bitcoinlib

…from 0.2.1 to 0.3.0

This, in conjunction with 478ce0, solves #554.

Solves #551.