Centralise loading default apps config file

Loading the config file after processing command line options can
cause problems, e.g. where an engine provides new ciphers/digests
these are not then recoginised on the command line. Move the
default config file loading to before the command line option
processing. Whilst we're doing this we might as well centralise
this instead of doing it individually for each application. Finally
if we do it before the OpenSSL_add_ssl_algorithms() call then
ciphersuites provided by an engine (e.g. GOST) can be available to
the apps.

RT#4085
RT#4086

Reviewed-by: Richard Levitte <levitte@openssl.org>