Teststand support

This PR is a few of changes that I found necessary and/or helpful for running cyclus in a test-stand sort of way.  Companion PR in cycamore.

* changed default module install log from lib/Models --> lib/cyclus
* dynamic modules are now searched for in lib/cyclus instead of cyclus install location (which turns out to search entire /usr directory if cyclus is installed there!)
* dynamic modules are searched for in CYCLUS_MODULE_PATH _before_ being searched for in default install location
* Timer does not reset listeners when init is called now - previously unintuitive behavior caused me trouble.
* Timer Reset method is now public and does a more thorough reset.
* newly registered listeners go onto a pending queue and aren't added to the active listeners until the beginning of the next timestep - this prevents iterator corruption with stl containers being modified while they are iterated over.