Translation of UI (german and english)

Bugfix for feeds
    - removed categories related and up
    - load new books now working
    - category random now working
login page is free of non accessible elements
boolean custom column is vivible in UI
books with only with certain languages can be shown
book shelfs can be deleted from UI
Anonymous user view is more resticted
Added browse of series in sidebar
Dependencys in vendor folder are updated to newer versions (licencs files are now present)
Bugfix editing Authors names
Made upload on windows working

cps/helper.py

@@ -18,6 +18,7 @@ from email.MIMEBase import MIMEBase
 from email.MIMEMultipart import MIMEMultipart
 from email.MIMEText import MIMEText
 from email.generator import Generator
+from flask_babel import gettext as _
 import subprocess
 
 def update_download(book_id, user_id):
@@ -72,8 +73,8 @@ def send_mail(book_id, kindle_mail):
     msg = MIMEMultipart()
     msg['From'] = settings["mail_from"]
     msg['To'] = kindle_mail
-    msg['Subject'] = 'Send to Kindle'
-    text = 'This email has been sent via calibre web.'
+    msg['Subject'] = _('Send to Kindle')
+    text = _('This email has been sent via calibre web.')
     msg.attach(MIMEText(text))
 
     use_ssl = settings.get('mail_use_ssl', 0)
@@ -95,7 +96,7 @@ def send_mail(book_id, kindle_mail):
             formats["pdf"] = os.path.join(config.DB_ROOT, book.path, entry.name + ".pdf")
 
     if len(formats) == 0:
-        return "Could not find any formats suitable for sending by email"
+        return _("Could not find any formats suitable for sending by email")
 
     if 'mobi' in formats:
         msg.attach(get_attachment(formats['mobi']))
@@ -104,13 +105,13 @@ def send_mail(book_id, kindle_mail):
         if filepath is not None:
             msg.attach(get_attachment(filepath))
         elif filepath is None:
-            return "Could not convert epub to mobi"
+            return _("Could not convert epub to mobi")
         elif 'pdf' in formats:
             msg.attach(get_attachment(formats['pdf']))
     elif 'pdf' in formats:
         msg.attach(get_attachment(formats['pdf']))
     else:
-        return "Could not find any formats suitable for sending by email"
+        return _("Could not find any formats suitable for sending by email")
 
     # convert MIME message to string
     fp = StringIO()
@@ -134,7 +135,7 @@ def send_mail(book_id, kindle_mail):
         mailserver.quit()
     except (socket.error, smtplib.SMTPRecipientsRefused, smtplib.SMTPException), e:
         app.logger.error(traceback.print_exc())
-        return "Failed to send mail: %s" % str(e)
+        return _("Failed to send mail: %s" % str(e))
 
     return None
 
@@ -154,8 +155,8 @@ def get_attachment(file_path):
         return attachment
     except IOError:
         traceback.print_exc()
-        message = ('The requested file could not be read. Maybe wrong '
-                   'permissions?')
+        message = (_('The requested file could not be read. Maybe wrong '\
+                   'permissions?'))
         return None
 
 def get_valid_filename(value, replace_whitespace=True):