LT-73 Export selected studies from study list to local

- Query to get metadata of the selected studies to export
- Download and zip the queried dicom files
- Show and update the progress dialog while querying and exporting studies

LesionTracker/.meteor/packages

@@ -51,3 +51,4 @@ check
 aldeed:template-extension@4.0.0
 zuuk:stale-session
 gilbertwat:bootstrap3-daterangepicker
+silentcicero:jszip

LesionTracker/.meteor/versions

@@ -97,6 +97,7 @@ rwatts:uuid@0.0.2
 service-configuration@1.0.5
 session@1.1.1
 sha@1.0.4
+silentcicero:jszip@0.0.4
 spacebars@1.0.7
 spacebars-compiler@1.0.7
 srp@1.0.4