Set environment in single place

Signed-off-by: Michal Čihař <michal@cihar.com>
Move composer setup to separate phase

Signed-off-by: Michal Čihař <michal@cihar.com>
Simplify if statements

Signed-off-by: Michal Čihař <michal@cihar.com>
Install ocular using composer instead of wget

Signed-off-by: Michal Čihař <michal@cihar.com>