fixed save button bug on new doc page, when a user clicks save now, it will save the new doc
delete the old editor div to fix the issue when a user clicks the new button on doc view, it will show the code editor now
add drop down for mode, set default value of theme in the drop down menu, set default mode for files with extension as .js .rb .java .html .css
 Bug fix of homepage and navbar: login buttons now show and hide depending on login status
Fixed UI related to 'Doc' and 'Folder' views
Merge pull request #41 from makersquare/parent_folder

Fixed UI related to Doc and Show Folder views
Merge pull request #44 from makersquare/nav_bar

Nav bar
Working chat emoji with guest user log in and github user log in.