Fix NetEvents compatibility

Some fixes for NetEvents compatibility.
1. If typed */pex reload* while using NetEvents, it created a infinite loop of requests between two or more servers (http://puu.sh/bC2Q1/f9222af341.png)
2. If typed  e.g. */pex group Guest add some.perm* (note: the capital 'G') other servers would execute `resetGroup("Guest")` instead of `resetGroup("guest")`

I added the argument `boolean callEvent` to `PermissionManager.reset` and changed all occurrences of `reset()`. I could also add a proxy function `reset()`, which calls `reset(true)`, if preferred.