Retire Python 3.3 support, reached EOL

Ref: https://www.python.org/downloads/release/python-337/

.travis.yml

@@ -1,6 +1,5 @@
 language: python
 python:
-  - "3.3"
   - "3.4"
   - "3.5"
   - "3.6"

README.md

@@ -84,7 +84,7 @@ PRs are welcome. Please visit [#233](https://github.com/jarun/Buku/issues/233) f
 
 | Feature | Dependency |
 | --- | --- |
-| Scripting language | Python 3.3+ |
+| Scripting language | Python 3.4+ |
 | HTTP(S) | urllib3 |
 | Encryption | cryptography |
 | Import browser exported html | beautifulsoup4 |

setup.py

@@ -5,8 +5,8 @@ import sys
 
 from setuptools import setup
 
-if sys.version_info < (3, 3):
-    print('ERROR: Buku requires at least Python 3.3 to run.')
+if sys.version_info < (3, 4):
+    print('ERROR: Buku requires at least Python 3.4 to run.')
     sys.exit(1)
 
 with open('buku.py', encoding='utf-8') as f:
@@ -52,9 +52,9 @@ setup(
         'Operating System :: OS Independent',
         'Programming Language :: Python :: 3',
         'Programming Language :: Python :: 3 :: Only',
-        'Programming Language :: Python :: 3.3',
         'Programming Language :: Python :: 3.4',
         'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: 3.6',
         'Topic :: Internet :: WWW/HTTP :: Indexing/Search',
         'Topic :: Utilities'
     ]

tests/test_bukuDb.py

@@ -1236,7 +1236,7 @@ def extract_all_from_zip_url(zip_url, tmp_zip, folder):
         zip_filename: Temporary zip file to save from url.
         folder: Extract all files inside this folder.
     """
-    with urllib.request.urlopen(zip_url) as response, open(tmp_zip.strpath, 'wb') as out_file:
+    with urllib.urlopen(zip_url) as response, open(tmp_zip.strpath, 'wb') as out_file:
         shutil.copyfileobj(response, out_file)
     zip_obj = zipfile.ZipFile(tmp_zip.strpath)
     zip_obj.extractall(path=folder.strpath)