Get rid of cachetools dependency

requirements.txt

 backports-datetime-fromisoformat==1.0.0
 cachecontrol==0.12.5
-cachetools==3.1.1
 commonmark==0.8.1
 ezodf==0.3.2
 Flask==1.0.2

setup.py

@@ -54,7 +54,6 @@ setup(
         'backports-datetime-fromisoformat',
 
         'cachecontrol',
-        'cachetools',
         'commonmark',
         'ezodf',
         'flask',

validata_ui/__init__.py

@@ -9,7 +9,6 @@ import flask
 import jinja2
 import requests
 import tableschema
-from cachetools.func import ttl_cache
 
 import opendataschema
 
@@ -18,9 +17,16 @@ from . import config
 log = logging.getLogger(__name__)
 
 
-@ttl_cache(maxsize=24, ttl=5*60)
-def schema_from_url(url):
-    return tableschema.Schema(url)
+def generate_schema_from_url_func(session):
+    """Generates a function that encloses session"""
+
+    def schema_from_url(url):
+        req = session.get(url)
+        req.raise_for_status()
+        schema_dict = req.json()
+        return tableschema.Schema(schema_dict)
+
+    return schema_from_url
 
 
 # And load schema catalogs which urls are found in config.json
@@ -28,6 +34,7 @@ schema_catalog_map = {}
 if config.HOMEPAGE_CONFIG:
     log.info("Initializing homepage sections...")
     caching_session = cachecontrol.CacheControl(requests.Session())
+    schema_from_url = generate_schema_from_url_func(caching_session)
     for section in config.HOMEPAGE_CONFIG['sections']:
         if isinstance(section['catalog'], str) and section['catalog'].startswith('http'):
             code = section['code']