fix references to ownCloud in the federations app

[schiessle]

cc @LukasReschke @MorrisJobke @blizzz please review

[MorrisJobke]

In #162 I changed the sentences that the federation isn't bound to our server anymore, because we also welcome 3rdparty implementations (like pydio) to federate with us :)

[schiessle]

at the moment you can't add a pydio as trusted server. But you will get a error message anyway, so it should be ok

[vincchan]

LGTM

[LukasReschke]

LGTM

[LukasReschke]

Conflicts. Yay ;)

[MorrisJobke]

This is superseeded by #162 (comment) for master (also see the comment there).

But @schiessle and I agreed on doing only a stupid search and replace (like in this PR) for stable9 to keep the existing translations.

I will close this now, because @schiessle is already working on the port of this to stable9 (cherry-picking doesn't work because of changed translations around the changed lines).