Moved vagrant-cachier from :box to :machine scope. [Fixes #650] [ci skip]
Fix typo.
icanhazip: use ipv4 subdomain to receive only ipv4 addresses

Signed-off-by: Thomas Stilwell <stilwellt@openlabs.co>
Drop external requirement: argparse.

* argparse is in Python's Standard Library since Python 2.7.
Merge pull request #657 from Renelvon/drop_argparse

Drop external requirement: argparse.
Merge pull request #634 from benemorius/icanhazipv4

[STANDBY] icanhazip: use ipv4 subdomain to receive only ipv4 addresses
Merge pull request #650 from patcon/560-machine-scope-caching

Switch vagrant-cachier cache scope to :machine
Add get_my_ip, is_ipv6_address and get_peer_url functions in network_util.py that will be used to refactor transactions.py
Refactor TransportLayer and CryptoPeerListener to use the new classes PeerListener and CryptoPeerListener