Adds bytestreamisd wrapper (#19)

* Adds bytestreamisd wrapper

* Missed case specific includes

bytestreamisd.i

+%module(package="csmapi") bytestreamisd
+%{
+    #include "BytestreamIsd.h"    
+%}
+
+%include "BytestreamIsd.h"
\ No newline at end of file

csmapi.i

@@ -9,3 +9,4 @@
 %include "rastergm.i"
 %include "plugin.i"
 %include "settableellipsoid.i"
+%include "bytestreamisd.i"

python/tests/test_api.py

+import csmapi
+import pytest
+
+def test_loadlib(loadlib):
+    assert loadlib is not None
+
+def test_streamisd():
+    print(dir(csmapi))
+    stream = "The is a stream."
+    isd = csmapi.BytestreamIsd(stream)
+    assert stream == isd.data()
+