[or]operator is deprecated in ocaml4
Merge pull request #512 from kumagi/master

hotfix: [or] operator is deprecated in ocaml4
Merge branch 'release/0.5.0'
re-enable gcc and master test in Travis CI (related #120)
disable gcc test in Travis (refs #120)
Merge branch 'release/0.5.1'
bump RPM packaging version
bump DEB packaging version
Merge branch 'master' into develop