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>

command.py

@@ -236,6 +236,7 @@ class InteractiveCommand(Command):
   """Command which requires user interaction on the tty and
      must not run within a pager, even if the user asks to.
   """
+
   def WantPager(self, _opt):
     return False
 
@@ -244,6 +245,7 @@ class PagedCommand(Command):
   """Command which defaults to output in a pager, as its
      display tends to be larger than one screen full.
   """
+
   def WantPager(self, _opt):
     return True