feat(.travis.yml): build js/input-method.js on-the-fly
feat(.travis.yml): build js/input-method.js on-the-fly

soonhokong/lean-tutorial,leanprover/tutorial,avigad/tutorial,fpvandoorn/tutorial,soonhokong/lean-tutorial,leanprover/tutorial,leanprover/tutorial,fpvandoorn/tutorial,fpvandoorn/tutorial,cjmazey/fork_leanprover_tutorial,Hodapp87/cs6460_project,Hodapp87/cs6460_project,soonhokong/lean-tutorial,Hodapp87/cs6460_project,cjmazey/fork_leanprover_tutorial,cjmazey/fork_leanprover_tutorial,avigad/tutorial,avigad/tutorial