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/grep.py

@@ -23,12 +23,14 @@ from command import PagedCommand
 from error import GitError
 from git_command import git_require, GitCommand
 
+
 class GrepColoring(Coloring):
   def __init__(self, config):
     Coloring.__init__(self, config, 'grep')
     self.project = self.printer('project', attr='bold')
     self.fail = self.printer('fail', fg='red')
 
+
 class Grep(PagedCommand):
   common = True
   helpSummary = "Print lines matching a pattern"
@@ -156,7 +158,6 @@ contain a line that matches both expressions:
                  action='callback', callback=carry,
                  help='Show only file names not containing matching lines')
 
-
   def Execute(self, opt, args):
     out = GrepColoring(self.manifest.manifestProject.config)