* openssl_certificate: Fix parameter assertion in Python3
Parameter assertion in Python3 is broken. pyOpenSSL get_X() functions
returns b'' type string and tries to compare it with '' string, leading
to failure.
The error mentionned above has been fixed by sanitizing the inputs from
a user to the assert only backend.
Also, this error was hidden by the fact that the improper check method
was called in the generate() functions.
* Add simple integration test for openssl_certificate
* remove subject == issuer assertion
* run integration tests only on supported hosts
* change min supported version to 0.15.x
* Add test for more CSR fields
* also convert dict members to bytes
* fix version_compare
* openssl_{csr, certificate}: Fail if pyOpenSSL <= 0.15
Previous 0.13 pyOpenSSL was a C-binding, and required the parameter
passed to add_extention to be in ASN.1. This has changed with the move
to 0.14 and it is now all pythong and string based.
Previous the 0.15 release, the `get_extensions()` method didn't exist,
since the modules rely heavily on it we ensure pyOpenSSL version is at
last 0.15.0.
* check pyopenssl version in openssl_csr integration test
