use click in trezorctl

.flake8

@@ -1,4 +1,7 @@
 [flake8]
+filename =
+    *.py,
+    trezorctl
 exclude =
     .tox/,
     build/,
@@ -11,6 +14,8 @@ ignore =
     F841,
     # F401: module imported but unused
     F401,
+    # E241: multiple spaces after ':'
+    E241,
     # E402: module level import not at top of file
     E402,
     # E501: line too long

.travis.yml

@@ -30,6 +30,7 @@ install:
 script:
     - python setup.py install
     - flake8
+    - flake8 trezorctl
     - tox
 
 notifications:

requirements.txt

@@ -3,3 +3,4 @@ protobuf>=3.1.0
 mnemonic>=0.17
 hidapi>=0.7.99.post20
 requests>=2.4.0
+click>=6.2

setup.py

@@ -7,6 +7,7 @@ install_requires = [
     'mnemonic>=0.17',
     'setuptools>=19.0',
     'requests>=2.4.0',
+    'click>=6.2'
 ]
 
 import sys

trezorlib/transport_udp.py

@@ -26,6 +26,8 @@ from .transport import TransportV2
 class UdpTransport(TransportV2):
 
     def __init__(self, device, *args, **kwargs):
+        if device is None:
+            device = ''
         device = device.split(':')
         if len(device) < 2:
             if not device[0]: