fix(frontends/lean/parser): readline compilation problem on Fedora19

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(frontends/lean/parser): allow parenthesis in level expressions

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
chore(travis): use another repository to fix luajit problem on ubuntu
chore(travis): use another repository to fix luajit problem on ubuntu