Improve image uploader UI

closes #1356
- add button to toggle back to uploader from image-url interface
- put save button next to url-input
- make box-height consistent
- position ui-elements to have equal padding all around to border
Replace cookieSession with session

- changed cookieSession to session
- added session.regenerate for login and logout
- added bookshelf session store
- added session table to database
- added import for databaseVersion 001
- added grunt task test-api
- cleanup of gruntfile to start express when needed only
- moved api tests to functional tests
add test for allowing 4 underscores in markdown
Modified ghostdown markdown extension to allow for 4+ inline underscores

See #1113
- added additional regex rule to replace 4+ underscores with their coded equivalent: &#95;
Merge pull request #1552 from bastilian/markdown-underscores

Modified ghostdown markdown extension to allow for 4+ inline underscores
Merge pull request #1548 from bastilian/improve_image_uploader_ui

Improve image uploader UI
Merge pull request #1247 from sebgie/bookshelf-session

Replace cookieSession with session