Use termcolor and colorama for CLI output

so that it works cross-platform

aptos/__main__.py

@@ -1,19 +1,21 @@
 import argparse
 import json
 import sys
+import colorama
 
+from termcolor import colored
 from .parser import SchemaParser
 from .primitive import Object
 from .visitor import ValidationVisitor
 from .schema.visitor import AvroSchemaVisitor
 
-
+''' previous color solution, not working in Windows
 class TermColors:
 
     GREEN = '\033[92m'
     RED = '\033[91m'
     DEFAULT = '\033[0m'
-
+'''
 
 def validate(arguments):
     with open(arguments.schema) as fp:
@@ -23,10 +25,8 @@ def validate(arguments):
     try:
         component.accept(ValidationVisitor(instance))
     except AssertionError as e:
-        sys.exit('{}error{} {!r}'.format(
-            TermColors.RED, TermColors.DEFAULT, e.args[0]))
-    print('{}success{} instance {!r} is valid against the schema {!r}'.format(
-        TermColors.GREEN, TermColors.DEFAULT, instance, arguments.schema))
+        sys.exit(colored('error', 'red') + ' {!r}'.format(e.args[0]))
+    print(colored('success', 'green') + ' instance {!r} is valid against the schema {!r}'.format(instance, arguments.schema))
 
 
 def convert(arguments):
@@ -42,6 +42,9 @@ def convert(arguments):
 
 
 def main():
+    # colorama works cross-platform to color text output in CLI
+    colorama.init()
+
     parser = argparse.ArgumentParser(description='''
         aptos is a tool for validating client-submitted data using the
         JSON Schema vocabulary and converts JSON Schema documents into