Do not register "Client"

"Enginio" is used in all places
Make EnginioClient unconstructible from QML

In QML EnginioQmlClient should be used
Merge pull request #85 from nierob/registrationFixes

Registration fixes
By default the client is initialized with the production api url
thus if using the staging API the requests fail because of invalid
certificate for https://api.staging.engin.io.

Check if the staging API is used every time the url is changed and
enable / disable ignoring the SSL certificates accordingly.
Create some objects for the fulltext search test
if no objects of the needed types exist.

This is useful if the tests are first ran on an empty backend.

NOTE: that setting the 'stringValue' property to be indexed still
has to be done manually from the dashboard after the first run.
Create some users before trying to use them
so that we do not end up with errors if the
backend is empty.