logDB provider

wrap the log storage as a provider
allow uses to config the logDB provider
add the ability to search the logs by message
rewrite the README.md and index.html to get rid of taffydb

Notes: 
search functionality is not very precise (i.e. not allow for substring searching) 
the db is not updated at the point when a new log is inserted


Use ```angular.noop``` rather than an empty function here.