Use swarming in capture_archives CT task and capture archives in parallel

ct/isolates/capture_archives.isolate

Index: ct/isolates/capture_archives.isolate
diff --git a/ct/isolates/create_pagesets.isolate b/ct/isolates/capture_archives.isolate
similarity index 80%
copy from ct/isolates/create_pagesets.isolate
copy to ct/isolates/capture_archives.isolate
index 8447766147539c0d2f17a83142c9c707dc06e593..37c6bda2bda8042c1b67881955fe1bcf0f6ea3e4 100644
--- a/ct/isolates/create_pagesets.isolate
+++ b/ct/isolates/capture_archives.isolate
@@ -4,16 +4,15 @@
 
 {
   'includes': [
-    'py.isolate',
   ],
   'conditions': [
     ['OS=="linux"', {
       'variables': {
         'files': [
-          '../../../../../bin/create_pagesets',
+          '../../../../../bin/capture_archives',
         ],
         'command': [
-          '../../../../../bin/create_pagesets',
+          '../../../../../bin/capture_archives',
           '-logtostderr',
           '--start_range=<(START_RANGE)',
           '--num=<(NUM)',