Remove logbook from the install_requires and other dependency areas

requirements.txt

@@ -1,4 +1,3 @@
 redis
 times
-logbook
 argparse

setup.cfg

@@ -1,2 +1,2 @@
 [bdist_rpm]
-requires = redis procname logbook
+requires = redis procname

setup.py

@@ -18,7 +18,6 @@ def get_version():
 
 def get_dependencies():
     deps = ['redis', 'times']
-    deps += ['logbook']  # should be soft dependency?
     if sys.version_info < (2, 7) or \
             (sys.version_info >= (3, 0) and sys.version_info < (3, 1)):
         deps += ['importlib']