feat(version): cache version to read from it not from file

vcsserver/__init__.py

@@ -17,13 +17,20 b''
 
 import os
 
+__version__ = ''
+
 
 def get_version():
+    global __version__
+    if __version__:
+        return __version__
+
     here = os.path.abspath(os.path.dirname(__file__))
     ver_file = os.path.join(here, "VERSION")
     with open(ver_file, "rt") as f:
         version = f.read().strip()
 
+    __version__ = version
     return version
 
 # link to config for pyramid