Bug 1296047 - Vagrant: Move helper functions to a symlinked .profile

This renames the existing `.bash_aliases` file to `.profile`, since
we're soon going to use it for more than just aliases. It overwrites the
default `.profile` file in the VM, so we need to source `.bashrc` as the
original did.

In addition, rather than copying the file we now symlink it, so that
future changes don't require a re-provision after pulling latest master
to take effect.

puppet/files/treeherder/.profile

@@ -1,3 +1,6 @@
+# Source .bashrc, since the default .profile we're replacing did so.
+. "$HOME/.bashrc"
+
 function thelp {
     echo "
     Treeherder-specific helpful aliases:

puppet/manifests/classes/treeherder.pp

@@ -28,8 +28,9 @@ class treeherder {
       user => "${APP_USER}",
     }
 
-    file {"${HOME_DIR}/.bash_aliases":
+    file {"$HOME_DIR/.profile":
-      source => "${PROJ_DIR}/puppet/files/treeherder/.bash_aliases",
+      ensure => "link",
+      target => "${PROJ_DIR}/puppet/files/treeherder/.profile",
       owner => "${APP_USER}",
       group  => "${APP_GROUP}",
     }