fix(incidents): adding more validations for add_incident()

* updated add_incident() with better string validations for json elements
* added new tests for checking these validations

Closes #18
fix(users): show updated team_list when adding a user

added team_list creation in __init__() of user_form to make sure its updated everytime teams are modified.

Closes #19
Merge pull request #20 from CitoEngine/develop

version 0.9.3 release for critical bugfixes