Improvements to XDebug config

In working with XDebug, I found that Nginx and/or PHP would kill the connection after 60s, making it difficult to track down those pesky bugs or get a good overview of what was happening in my applications.  This commit does the following, to make things a little easier in that regard:

* Enable Xdebug sessions up to one hour on a single request
* Increase memory limits a little bit - also sneaks in a max_upload_file_size increase (these are DEV machines after all)
* Don't auto-start XDebug (we don't necessarily want every request to run through our IDE)