Add decorator expected_errors for security_group extension

This patch add decorator expected_errors for all the APIs of
security_group that required by v2.1 API.

Partially implements blueprint v2-on-v3-api

Change-Id: I6ccf9f3b7d7137948d16481d82d00220a27d8541
Fix the cell API with string rpc_port failed

When cell create/update accept rpc_port as string, it will
return 500. This patch add code to covert the string as integer.

Change-Id: I8ace46731ac02f810b978c54843b6e137c9882be
Closes-Bug: #1389933
Limit tcp/udp port to be empty string in json-schema

tcp/udp port can be string and integer. Currently the json-schema accept
string, but it didn't limit the length of string, so there can be pass
emtpy string as tcp/udp port. This patch add string length limit to it.

Change-Id: I6c338a2417ae5f8817b24823b3d745dc1e0fbd58
Merge "Add decorator expected_errors for security_group extension"
Merge "Fix the cell API with string rpc_port failed"
Merge "Limit tcp/udp port to be empty string in json-schema"