pep8 cleanup

A few tweaks for pep8 since the pep8 tox target is failing with a number of warnings

### Before:

```
$ tox -e pep8
pep8 develop-inst-nodeps: /Users/marca/dev/git-repos/python-memcached
pep8 runtests: commands[0] | flake8
./memcache.py:1:1: H803  git commit title ('Resolving conflicts from cabrera-py33_fixes.') should not end with period
./memcache.py:51:1: H306  imports not in alphabetical order (sys, socket)
./memcache.py:53:1: H306  imports not in alphabetical order (time, binascii)
./memcache.py:59:1: H305  imports not grouped correctly (zlib: stdlib, six: third-party)
./memcache.py:59:1: H306  imports not in alphabetical order (zlib, six)
./memcache.py:75:5: F401 'compress' imported but unused
./memcache.py:75:30: H301  one import per line
./memcache.py:86:1: H302  import only modules.'from io import BytesIO' does not import a module
./memcache.py:541:1: H405  multi line docstring summary not separated with an empty line
./memcache.py:554:1: H405  multi line docstring summary not separated with an empty line
./memcache.py:682:1: H405  multi line docstring summary not separated with an empty line
./memcache.py:689:1: H405  multi line docstring summary not separated with an empty line
./memcache.py:886:50: H904  Wrap long lines in parentheses instead of a backslash
./memcache.py:1163:1: H405  multi line docstring summary not separated with an empty line
./memcache.py:1173:21: E126 continuation line over-indented for hanging indent
./memcache.py:1179:40: H904  Wrap long lines in parentheses instead of a backslash
./memcache.py:1362:5: H305  imports not grouped correctly (doctest: stdlib, memcache: project)
./memcache.py:1388:80: E501 line too long (85 > 79 characters)
./memcache.py:1414:38: E227 missing whitespace around bitwise or shift operator
./memcache.py:1422:31: E711 comparison to None should be 'if cond is None:'
./memcache.py:1431:9: E265 block comment should start with '# '
./memcache.py:1514:15: H201  no 'except:' at least use 'except Exception:'
./memcache.py:1519:9: F402 import 'pickle' from line 55 shadowed by loop variable
./memcache.py:1532:30: E711 comparison to None should be 'if cond is None:'
./memcache.py:1538:30: E711 comparison to None should be 'if cond is None:'
./setup.py:19:9: E121 continuation line under-indented for hanging indent
./tests/test_setmulti.py:5:1: E265 block comment should start with '# '
./tests/test_setmulti.py:14:1: H307  like imports should be grouped together (unittest and sys from stdlib are separated by whitespace)
./tests/test_setmulti.py:17:1: H305  imports not grouped correctly (memcache: project, socket: stdlib)
ERROR: InvocationError: '/Users/marca/dev/git-repos/python-memcached/.tox/pep8/bin/flake8'
```

### After:

```
$ tox -e pep8
pep8 develop-inst-nodeps: /Users/marca/dev/git-repos/python-memcached
pep8 runtests: commands[0] | flake8
./memcache.py:76:5: F401 'compress' imported but unused
./memcache.py:76:30: H301  one import per line
./memcache.py:87:1: H302  import only modules.'from io import BytesIO' does not import a module
./memcache.py:696:1: H405  multi line docstring summary not separated with an empty line
./memcache.py:1372:5: H305  imports not grouped correctly (doctest: stdlib, memcache: project)
```