Stem CI: remove 0.3.4 builds; add 0.4.1
Hi! Our {maint,release}-0.3.4 branches are now EOL; our {maint,release}-0.4.1 branches are now separate from master. Stem may wish to update its travis configuration accordingly.
(I am opening this ticket because our draft EndOfLifeTor.md document tells me I should do this when a branch reaches EOL. If that's wrong, please let me know.)