added install script (#19)

install_script.py

@@ -0,0 +1,39 @@
+from urllib.request import urlopen
+from sys import platform as _platform
+import os
+
+def download_txt_url(path_to_file, url):
+    with urlopen(url) as stream:
+        CHUNK = 2 ** 14
+        with open(path_to_file, 'wb') as outfile:
+            while True:
+                chunk = stream.read(CHUNK)
+                if not chunk:
+                    break
+                outfile.write(chunk)
+
+
+if _platform == "linux" or _platform == "linux2" or _platform == "darwin":
+	bin_shi7en = 'ninja_shi7_linux'
+	bin_split = 'gotta_split_s_linux'
+elif _platform == "darwin":
+	bin_shi7en = 'ninja_shi7_mac'
+	bin_split = 'gotta_split_mac'
+elif _platform == "win32":
+	bin_shi7en = 'ninja_shi7.exe'
+	bin_split = 'gotta_split_s.exe'
+else:
+	print('Undefined OS\n')
+	raise SystemExit()
+
+old_shi7en_bin =  'https://github.com/knights-lab/shi7en/releases/download/0.0.1/' + bin_shi7en
+new_shi7en_bin = 'shi7en_trimmer'
+old_split_bin = 'https://github.com/knights-lab/shi7en/releases/download/0.0.1/' + bin_split
+new_split_bin = 'gotta_split'
+download_txt_url(new_shi7en_bin, old_shi7en_bin)
+download_txt_url(new_split_bin, old_split_bin)
+os.chmod(new_shi7en_bin, 0o755)
+os.chmod(new_split_bin, 0o755)
+
+#TODO: maybe add $PATH 
+