Fix PrivateKey encoding in certservice-client, refactor CsrFactory

Add PrivateKeyToPemEncoder with tests
Refactor CsrFactory to return not encoded PEM string (less responsibility and easier to test later)

Issue-ID: AAF-996
Change-Id: Ia8124d43ef7fb8b1d3077c98929c52f30b6512c6
Signed-off-by: Remigiusz Janeczek <remigiusz.janeczek@nokia.com>
9 files changed