added explicit state for isDirty and hasRemoteChanges to models

Updated the views, mixins, and templates
fix when remotely-updated is set, style the icons

change commitSha to blobSha to more accurately describe the sha stored
only set save if the dirty bit is set to true, remove asterisk from chapters
Merge pull request #16 from oerpub/phil-state-icons

Add icons in the ToC, picker, and workspace to show the dirty/remotely-updated state of content