Add nimscript test and run it in Travis CI

tests/test_nimscript.nims

@@ -0,0 +1,25 @@
+# This nimscript is used to test if the following modules can be imported
+# http://nim-lang.org/docs/nims.html
+
+import algorithm
+import base64
+import colors
+import hashes
+import lists
+import math
+# import marshal
+import options
+import ospaths
+# import parsecfg
+# import parseopt
+import parseutils
+import pegs
+import queues
+import sequtils
+import strutils
+import subexes
+import tables
+import unicode
+import uri
+
+echo "Nimscript imports are successful."