Update App::Env::ASCDS to 0.04_ska and Ska::AGASC to 3.4

App::Env::ASCDS includes logic to use DS8.5 on all platforms except
CentOS6 64-bit.  CentOS6 64-bit systems will get the ASCDS default.

Ska::AGASC 3.4 allows a pass-thru of the APP_ENV_ASCDS_STR environment
variable if one wishes to override App::Env::ASCDS in testing.