(refactor) Modularized store from ind session.
(doc) Modularized session and store.
(feat) Added HashSessionStore.
(refactor) Fixed example for HashSessionStore.
(test) Updated for HashSessionStore.
(refactor) Refactored for chain.link.
Merge pull request #7 from zzmp/refactor/division-of-labor

(refactor) Division of labor.