Fix #18, update combobox Javascript.

Updated 'bootstrap-combobox.js' based on a version that allows free-form
input, here: https://github.com/aayers-fender/bootstrap-combobox
/blob/04414c6b94b658f742758f1672a1b4e4befc2f5c/js/bootstrap-combobox.js.

Updated step3 Javascript so new button click copies value of dropdown
into textbox in dialog box.  Also set focus on textbox in 'shown'
event of dialog box.