Fix Gulp build

• Update project to build on modern Node
• Removed bower dependency
• Updated some dev dependencies

Support added for alternative base installation URIs

Now the "Send to OmniFocus" button works for JIRA installations that are installed into a subdirectory of some host. For example: http://myhost.com/path/to/jira/....

Fix for HTTPS-hosted JIRA installs

This release fixes an issue that occurs when accessing JIRA over HTTPS.

When accessing a page via HTTPS, Chrome will refuse to load assets via HTTP (unless you execute the browser with the special --allow-running-insecure-content flag). The app URLs used to create tasks, which employ the omnifocus or mailto schemas, used to be called from the content.js file, which executes in an environment with full access to the user's document, so chrome would block their invocation.

To solve this, the calls to these URLs were moved to the events.js script, which runs in isolation from the user's document, and hence does not get blocked by Chrome.

Thanks to @mattstratton, @aquarion, and @jkjelsbak for their assistance identifying the problem and to @aquarion for helping confirm the fix.

The Mail Drop release!

This release adds an options screen which allows you enter the Mail Drop address of your Omni Sync Server account, so you can send JIRA tasks to your OmniFocus Inbox from any computer, regardless of OS.