Fix bug in python3.4: 'dict_keys' object does not support indexing

Fix bug in python3.4: 'dict_keys' object does not support indexing

In python3.4, dictory's function of key() return value is a dict_key object, not list, so the follow code will be error:
    dict x = {1:11, 2:22, 3;33}
    y= x.keys()[0]
 the error is TypeError: 'dict_keys' object does not support indexing, the correct expression is below:
    y = list(x.keys())[0]

So parser's code will be modified refer to above.

Change-Id: I41e0c28167c7823fc735aaf3afc78c1a9a15e9e0
JIRA: PARSER-64
Signed-off-by: shangxdy <shang.xiaodong@zte.com.cn>