Add flake8-ycm to test requirements

Fix errors reported by flake8-ycm.

python/test_requirements.txt

@@ -1,5 +1,6 @@
 flake8                >= 3.0.0
 flake8-comprehensions >= 1.4.1
+flake8-ycm            >= 0.1.0
 mock                  >= 1.0.1
 nose                  >= 1.3.7
 PyHamcrest            >= 1.8.0

python/ycm/vimsupport.py

@@ -977,7 +977,8 @@ def InsertNamespace( namespace ):
 def SearchInCurrentBuffer( pattern ):
   """ Returns the 1-indexed line on which the pattern matches
   (going UP from the current position) or 0 if not found """
-  return GetIntValue( "search('{0}', 'Wcnb')".format( EscapeForVim( pattern )))
+  return GetIntValue(
+    "search('{0}', 'Wcnb')".format( EscapeForVim( pattern ) ) )
 
 
 def LineTextInCurrentBuffer( line_number ):