Cert dialog: display validity in details
Change public API to allow chaining of *one* TrustManager

The previous implementation was erroneous, it only did honor
the first TrustManager parameter until a certificate was stored in
MTMs keystore. After that, only the second parameter was used.

If somebody should have demand for more than one chained TM, this
warrants a new, correct, API.
README: fixed documentation, added HV
Spanish Translation by kruks23
German Translation