Add dropbox CSP directive if configured and make button clickable

The lack of a 'preventDefault' on the click event handler resulted in the dropbox link being unclickable.
Furthermore because of a missing CSP rule, the dropbox script couldn't be loaded. The dropbox origin is now added to the CSP script sources if dropbox integration is configured.

Signed-off-by: Erik Michelson <github@erik.michelson.eu>

lib/csp.js

@@ -32,6 +32,10 @@ var googleAnalyticsDirectives = {
   scriptSrc: ['https://www.google-analytics.com']
 }
 
+var dropboxDirectives = {
+  scriptSrc: ['https://www.dropbox.com']
+}
+
 CspStrategy.computeDirectives = function () {
   var directives = {}
   mergeDirectives(directives, config.csp.directives)
@@ -39,6 +43,7 @@ CspStrategy.computeDirectives = function () {
   mergeDirectivesIf(config.useCDN, directives, cdnDirectives)
   mergeDirectivesIf(config.csp.addDisqus, directives, disqusDirectives)
   mergeDirectivesIf(config.csp.addGoogleAnalytics, directives, googleAnalyticsDirectives)
+  mergeDirectivesIf(config.dropbox.appKey, directives, dropboxDirectives)
   if (!areAllInlineScriptsAllowed(directives)) {
     addInlineScriptExceptions(directives)
   }

public/js/index.js

@@ -996,7 +996,8 @@ ui.toolbar.export.snippet.click(function () {
     })
 })
 // import from dropbox
-ui.toolbar.import.dropbox.click(function () {
+ui.toolbar.import.dropbox.click(function (event) {
+  event.preventDefault()
   var options = {
     success: function (files) {
       ui.spinner.show()