Fix various DeprecationWarnings discovered with tox

data/home/vhaenel/git-working/graphite-web/webapp/graphite/render/grammar.py:98: DeprecationWarning: Operator '<<' is deprecated, use '<<=' instead
  expression << Group(call | pathExpression)('expression')
/data/home/vhaenel/git-working/graphite-web/webapp/graphite/render/grammar.py:99: DeprecationWarning: Operator '<<' is deprecated, use '<<=' instead
  grammar << expression
Creating test database for alias 'default'...
2014-03-21 11:48:21.773028-05:00
/data/home/vhaenel/git-working/graphite-web/webapp/graphite/cli/parser.py:51: DeprecationWarning: Operator '<<' is deprecated, use '<<=' instead
  fcall << Combine( Word(alphas) + Literal('(') + arg + ZeroOrMore(',' + arg) + Literal(')') )
/data/home/vhaenel/git-working/graphite-web/webapp/graphite/cli/parser.py:136: DeprecationWarning: Operator '<<' is deprecated, use '<<=' instead
  gsave_cmd | dogsave_cmd | gload_cmd | graphs_cmd | rmgraph_cmd | Empty() \
.No handlers could be found for logger "cache"
Merge pull request #665 from esc/fix/python2.6_deprecation_warnings

Fix various DeprecationWarnings discovered with tox