Make Session lifetime rely on remember_me_seconds

The Session lifetime shouldn't rely on ````gc_maxlifetime```` parameters
This parameters should only be used for if ````remember_me_seconds```` is not defined.
Now, the session lifetime rely on remember_me_secons instead of remember_me_seconds.
Note that the old parameter ````saveHandler.options.lifetime```` seemed to be unused.
Set lifetime parameter using options.lifetime
Set lifetime parameter using options.lifetime

If lifetime option is empty or unsetted, the value is setted to ````gc_maxlifetime````
Merge pull request #15 from Massamba/1.4.x

Use lifetime option for the Session