Implemented python gojsonnet get_version

setup.py

@@ -23,8 +23,17 @@ LIB_DIR = DIR + '/c-bindings'
 MODULE_SOURCES = ['cpp-jsonnet/python/_jsonnet.c']
 
 def get_version():
-    # TODO think about it (how to get the version)
-    return '0.14.0'
+    """
+    Parses the version out of libjsonnet.h
+    """
+    with open(os.path.join(DIR, 'vm.go')) as f:
+        for line in f:
+            if 'const' in line and 'version' in line:
+                v_code = line.partition('=')[2].strip('\n "')
+                if v_code[0] == 'v':
+                    return v_code[1:]
+
+    return None
 
 class BuildJsonnetExt(BuildExt):
     def run(self):

vm.go

@@ -124,6 +124,9 @@ const (
 	evalKindStream           = iota
 )
 
+// version is the current gojsonnet's version
+const version = "v0.14.0"
+
 // Evaluate evaluates a Jsonnet program given by an Abstract Syntax Tree
 // and returns serialized JSON as string.
 // TODO(sbarzowski) perhaps is should return JSON in standard Go representation
@@ -253,5 +256,5 @@ func SnippetToAST(filename string, snippet string) (ast.Node, error) {
 
 // Version returns the Jsonnet version number.
 func Version() string {
-	return "v0.14.0"
+	return version
 }