Added Password validation check

[shivani-orch]

We have fixed this OWASP issue - The application accepts very weak passwords like 'test'.
Strong password policy has been implemented - min8 char password consist of letter, special char, number etc

[amanda11]

Does this only enforce password rule on stdin, not via the password parameter? It would seem wrong to only enforce policy interactively and not on command line.

Also in st2-bootstrap the default if they don't specify is still Ch@ngeMe, which wouldn't match the policy - if the policy requires a number.

Has the password policy been agreed? In particular, the fact that the chosen policy breaks the default password that is used throughout many repos (including this repo in st2_bootstraph.sh).

Therefore if this password policy is agreed, then I think before it can be implemented, all other places in the different repos that use the current default password will need updating first - to prevent breakages. e.g its used in at least st2ci/st2cd/st2/st2vagrant/st2-docker/packer-st2 - and many more.
Alternatively a password policy that required special character or digit rather than both, would prevent the requirement to change all the other repos.

[CLAassistant]

All committers have signed the CLA.