Specify gflags in readme and versions in setup

Author: fahhem

README.rst

@@ -27,6 +27,7 @@ Cons:
 
 Dependencies:
   * libusb1 (1.0.16+)
+  * python-gflags (2.0+)
   * python-libusb1 (1.2.0+)
   * python-progressbar (for fastboot_debug, 2.3+)
   * python-m2crypto (0.21.1+)

setup.py

@@ -43,7 +43,11 @@
 
     keywords = ['android', 'adb', 'fastboot'],
 
-    requires = ['python-gflags', 'libusb1', 'M2Crypto'],
+    requires = ['python-gflags>=2.0', 'libusb1>=1.0.16', 'M2Crypto>=0.21.1'],
+
+    extra_requires = {
+        'fastboot': 'progressbar>=2.3'
+    },
 
 ## classifier list https://pypi.python.org/pypi?:action=list_classifiers
     classifiers = [