Work on refactoring measurements out of Lesion Tracker package

- Removed AssociatedStudies Collection
- Measurement API is generated from configuration files
- Data exchange methods are defined in configuration

Packages/ohif-viewerbase/client/components/basic/removableBackdrop/removableBackdrop.html

@@ -0,0 +1,7 @@
+<template name="removableBackdrop">
+    <div class="removableBackdrop noselect"
+        oncontextmenu='return false;'
+        unselectable='on'
+        onselectstart='return false;'>
+    </div>
+</template>

Packages/ohif-viewerbase/client/components/basic/removableBackdrop/removableBackdrop.styl

@@ -0,0 +1,9 @@
+.removableBackdrop
+  position: fixed
+  top: 0
+  right: 0
+  bottom: 0
+  left: 0
+  z-index: 50
+  background-color: transparent
+