Fix blank line issues reported by flake8

- E301 expected 1 blank line
- E302 expected 2 blank lines
- E303 too many blank lines
- E305 expected 2 blank lines after class or function definition
- E306 expected 1 blank line before a nested definition

Fixed automatically with autopep8:

  git ls-files | grep py$ | xargs autopep8 --in-place \
    --select E301,E302,E303,E305,E306

Manually fix issues in project.py caused by misuse of block comments.

Change-Id: Iee840fcaff48aae504ddac9c3e76d2acd484f6a9
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/254599
Reviewed-by: Mike Frysinger <vapier@google.com>
Tested-by: David Pursehouse <dpursehouse@collab.net>

subcmds/stage.py

@@ -21,6 +21,7 @@ from color import Coloring
 from command import InteractiveCommand
 from git_command import GitCommand
 
+
 class _ProjectList(Coloring):
   def __init__(self, gc):
     Coloring.__init__(self, gc, 'interactive')
@@ -28,6 +29,7 @@ class _ProjectList(Coloring):
     self.header = self.printer('header', attr='bold')
     self.help = self.printer('help', fg='red', attr='bold')
 
+
 class Stage(InteractiveCommand):
   common = True
   helpSummary = "Stage file(s) for commit"
@@ -105,6 +107,7 @@ The '%prog' command stages files to prepare the next commit.
         continue
     print('Bye.')
 
+
 def _AddI(project):
   p = GitCommand(project, ['add', '--interactive'], bare=False)
   p.Wait()