Refactor and fix beautifulsoup version selection in the parser

it cared for six.PY3 which has little to do with the beautifulsoup version

compressor/parser/beautifulsoup.py

@@ -1,36 +1,34 @@
 from __future__ import absolute_import
 from django.core.exceptions import ImproperlyConfigured
-from django.utils import six
 from django.utils.encoding import smart_text
 
-from compressor.exceptions import ParserError
 from compressor.parser import ParserBase
-from compressor.utils.decorators import cached_property
 
 
 class BeautifulSoupParser(ParserBase):
 
-    @cached_property
-    def soup(self):
+    def __init__(self, content):
+        super(BeautifulSoupParser, self).__init__(content)
         try:
-            if six.PY3:
-                from bs4 import BeautifulSoup
-            else:
+            from bs4 import BeautifulSoup
+            self.use_bs4 = True
+            self.soup = BeautifulSoup(self.content, "html.parser")
+        except ImportError:
+            try:
                 from BeautifulSoup import BeautifulSoup
-            return BeautifulSoup(self.content)
-        except ImportError as err:
-            raise ImproperlyConfigured("Error while importing BeautifulSoup: %s" % err)
-        except Exception as err:
-            raise ParserError("Error while initializing Parser: %s" % err)
+                self.use_bs4 = False
+                self.soup = BeautifulSoup(self.content)
+            except ImportError as err:
+                raise ImproperlyConfigured("Error while importing BeautifulSoup: %s" % err)
 
     def css_elems(self):
-        if six.PY3:
+        if self.use_bs4:
             return self.soup.find_all({'link': True, 'style': True})
         else:
             return self.soup.findAll({'link': True, 'style': True})
 
     def js_elems(self):
-        if six.PY3:
+        if self.use_bs4:
             return self.soup.find_all('script')
         else:
             return self.soup.findAll('script')