setup: add dependency for libusb1

requirements.txt

@@ -1,7 +1,7 @@
 ecdsa>=0.9
 mnemonic>=0.17
-hidapi>=0.7.99.post20
 requests>=2.4.0
 click>=6.2
 pyblake2>=0.9.3
+hidapi>=0.7.99.post20
 libusb1>=1.6.4

setup.py

@@ -2,9 +2,9 @@
 from setuptools import setup
 
 install_requires = [
+    'setuptools>=19.0',
     'ecdsa>=0.9',
     'mnemonic>=0.17',
-    'setuptools>=19.0',
     'requests>=2.4.0',
     'click>=6.2',
     'pyblake2>=0.9.3',
@@ -16,6 +16,11 @@ if '--disable-hidapi' in sys.argv:
 else:
     install_requires.append('hidapi>=0.7.99.post20')
 
+if '--disable-libusb' in sys.argv:
+    sys.argv.remove('--disable-libusb')
+else:
+    install_requires.append('libusb1>=1.6.4')
+
 from trezorlib import __version__ as VERSION
 
 setup(