Better looking sign in, check for expired token

Tweaked the styles with the help of a bootstrap demo to create
a nicer looking sign in form. The loginService also does an API
call to check if the stored authtoken is still valid or if a login
is necassary.
Added method to authAPI, dbManage singleton

AuthAPI now has a check() method that can be called and will return
true or false if the provided authentication token is still valid.
dbManage is now coded to be gotten by using a static getInstance()
method which will return a singleton object. Database management is
a perfectly reasonable place to have a singleton object. This forces
a single database connection and also prevents tons of dbManage
instances littering the code. Right now the bootstrap file and the
authentication class/auth api module are reconfigured to use the
new singleton. The others will be converted with time.