Folder organization fix + export_to_file
- Moved packet unit test to tests/
- Removed __pycache__ from the repository
- Implemented export_to_file() function for RealTimeGraph
Moved plotting function inside RealTimeGraph
Added flow_id attribute to packets.

This allows hosts to pass along the packet to the correct flow.
Updated doctrings.

Changed indentation and formatting to mimic other files in our repo.
Merge branch 'master' into Output

Conflicts:
	__pycache__/Packet.cpython-34.pyc
Merge branch 'Output'
Fixed packet lengths and Python 2.7 compatibility

Data packets, acknowledgment packets, routing update packets, and FIN
packets have a fixed length of 1024, 1024, 64, and 64 bytes,
respectively.

PacketTypes enum was rewritten as an internal class of the general
Packet class. This removes the reliance on Python 3.4, so we can now
commit to developing on Python 2.7.
[Link] Add implementation details and documentation
Committing pycache since I can't sync with master...
Merge branch 'Packet' of github.com:kexinrong/NetworkSimulator into Packet
Merge branch 'master' into Packet

Conflicts:
	__pycache__/Packet.cpython-34.pyc
Merge branch 'Packet'
Merge branch 'master' into Packet
Merge branch 'Packet'
[Link] Add implementation details and documentation
Merge branch 'master' of https://github.com/kexinrong/NetworkSimulator

Conflicts:
	__pycache__/Packet.cpython-34.pyc
Merge branch 'master' of github.com:kexinrong/NetworkSimulator
Merge branch 'master' into Link