Now supports running under a sub path

Just set the SPOOLMAN_BASE_PATH environment variable and it should work.

Resolves #95

.env.example

@@ -35,6 +35,11 @@
 SPOOLMAN_HOST=0.0.0.0
 SPOOLMAN_PORT=7912
 
+# Change base path
+# Set this if you want to host Spoolman at a sub-path
+# If you want the root to be e.g. myhost.com/spoolman
+# Then set this to /spoolman
+#SPOOLMAN_BASE_PATH=
 
 # Enable Collect Prometheus metrics at database
 # Default: FALSE