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


I saw some code in debugger.js where the jquery is used. in debugger, jquery has been used to set the css and resize the height of the debugger. Should we still skip it?