Bupt branch merge

1. Detect internet environment, change ubuntu source if it is in China
2. ssh.py is downloaded from bupt server, as the repository on github is blocked in China.
3. SPGW is switched to master branch, revision "head" (using kernel 4.7)
4. OAISIM info is written into database when HSS installed.
5. HSS is switched to master branch
6. Some other config file tweaks.