self signed generated cert has 30d expiration instead of intended 3650

[JuanJo Ciarlante]

Provided openssl.cnf doesn't work as expected:

$ head -5 data/openssl.cnf
RANDFILE = /dev/urandom

[ req ]
default_days = 3650
default_bits = 1024

# replaying usage from charm when SELFSIGNED is set:
$ OPENSSL_CN=foo OPENSSL_PUBLIC=1.2.3.4 OPENSSL_PRIVATE=5.6.7.8 openssl req -new -x509 -nodes -config data/openssl.cnf -keyout foo.key -out foo.crt
Generating a 1024 bit RSA private key
...++++++
..................................................++++++
writing new private key to 'foo.key'
-----
$ openssl x509 -in foo.crt -noout -dates
notBefore=Jan 8 23:37:56 2015 GMT
notAfter=Feb 7 23:37:56 2015 GMT

FYI https://www.openssl.org/docs/apps/req.html states
"-days n : when the -x509 option is being used this specifies the number of days ..."

So, because indeed the charm needs to use -x509, it should
add "-days 3650" to the cmdline invocation, instead of
relying on the (unused) openssl.cnf default_days value.