Add 'always hide CC drawer' option

When the CC starts up, it opens the drawer by default. The option
introduced by this commit closes it as soon as the content script gets
injected into the page.

Feature suggested at pekb/thread/67965396?msgid=69642485

Fixes: #10
Change-Id: I2a043dc9888eee2c9b1f98713d36cd1a49d3c931
diff --git a/src/common/common.js b/src/common/common.js
index f1366b1..1a67bca 100644
--- a/src/common/common.js
+++ b/src/common/common.js
@@ -17,6 +17,7 @@
   'ccdarktheme': false,
   'ccdarktheme_mode': 'switch',
   'ccdarktheme_switch_enabled': true,
+  'ccforcehidedrawer': false,
 };
 
 const specialOptions = [