Fix stack traces on Node 0.10.

.mocha.js

@@ -0,0 +1,3 @@
+try { require('clarify') } catch (_) {}
+try { require('trace') } catch (_) {}
+try { require('source-map-support/register') } catch (_) {}

.mocha.opts

@@ -1,3 +1 @@
---require clarify
---require trace
---require source-map-support/register
+--require ./.mocha.js

index.js

@@ -7,10 +7,10 @@ if (process.env.DEBUG === undefined) {
   process.env.DEBUG = 'app-conf,xen-api,xo:*'
 }
 
-// Better stack traces.
-require('clarify')
-require('source-map-support/register')
-require('trace')
+// Better stack traces if possible.
+try { require('clarify') } catch (_) {}
+try { require('source-map-support/register') } catch (_) {}
+try { require('trace') } catch (_) {}
 
 // Import the real main module.
 module.exports = require('./dist')