Added notes field to Machine model. refs #127
Added migration for new Machine notes field. fixes # 127
Added apache access root path to Machine model. refs #128
Added DB migration for new apache access root path for Machine model. Fixes #128
Rewrote/renamed Bag method to render access url based on its Machine's Apache ro
ot and the bag's path from the file system root. Fixes #129
Merge pull request #130 from gwu-libraries/machine-model-changes

Machine model changes