issue2551029: Jinja2 template install error. Issue where template's config.ini not getting updated. Change do_install in admin.py to load config_ini.ini from template before writing tracker's config.ini. This generates an updated config file for the user on install preserving values required tomake tracker work. Added config_ini.ini files to jinja2 and responsive templates to set required values (template_engine and static_files; static_files resp.). Documented new file in doc/tracker_templates.txt and added tests for new admin.py code.

def init_severity(db, cl, nodeid, newvalues):
    """Make sure severity is set on new issues"""
    if 'severity' in newvalues and newvalues['severity']:
        return

    normal = db.severity.lookup('normal')
    newvalues['severity'] = normal

def init(db):
    db.issue.audit('create', init_severity)