Remove t() from role, escape properly (not a security threat)

Hi/Ahoj :-)

User submitted strings (which role name definitely is) should never be passed to t(). I also added check_plain() to it. It's not a security threat/bug, because roles are always created by administrator, but let's do this the right way and be sure.

Attaching a patch. I also fixed one english typo and removed $role_varname, as you never used it.

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Jakub Suchy