Update version number to 3.3.1

Fix: downgrade glibc

Update version number

Update version number

Fix: node js version

Modify: set node_js version to node_js in travis.yml

Modify: check static file version when statics folder exists

Feat: check new versions while booting

Update: submodule

Merge branch 'master' of https://github.com/cloudreve/Cloudreve