Rename data-store exports for consistency

Rename download to downloadSounding. Update in worker.
Rename preprocess to preprocessSounding. Update in worker.
Remove parse from worker.
Switch to function expressions for consistency.
Skeleton framework for post-cache strategy.
Implement data-store putCache.
Implement data-store getCache.
Implement data-store clearCache.
Implement data-store extractSounding

Remove unneeded functions and vars from old parseSounding. Remove
database update code from closeHandler. Add skeletons for required
getFilename and setFilename that will manage the file database.
Implement data-store getFilename and setFilename.
Implement data-store getSounding.
Add file management to data-store preprocessor.
Add time and location to sounding before caching.
Add attribution to mapView. See #24
Update navbar to bootstrap 3 syntax.
Fix bug in getSounding.
Add sounding retrieval to worker. Closes #27
Merge branch 'post-cache' into develop. Closes #36