cleaning the pacs_pull plugin and move dicom listener to core

dicom listener is being move because it is a core feature, not plugin specific.
even without a pacs_pull/push plugin, one can send dicom data to chris, via this listener
Merge branch 'master' of https://github.com/FNNDSC/chrisreloaded
move process.php to core
fix commit 8834410262e182a7313554d488b707fcc1b4550e

we need the '/' at the end of the CHRIS_DATA with CHRIS_HOME
fix commit 8834410262e182a7313554d488b707fcc1b4550e

we need the '/' at the end of the CHRIS_TMP with CHRIS_HOME
fix commit 8834410262e182a7313554d488b707fcc1b4550e

we need the '/' at the end of the CHRIS_USERS with CHRIS_HOME
fix commit 8834410262e182a7313554d488b707fcc1b4550e

we need the '/' at the end of the CHRIS_LOG with CHRIS_HOME