Sharing optimization

Change the storage and display of sharings to improve the time needed to generate the page.
Instead of looking for a default value when displaying the sharing links, they are added
during the configuration.
Change test
Add a test to avoid warnings in log
Sharing optimization

Change the storage and display of sharings to improve the time needed to generate the page.
Instead of looking for a default value when displaying the sharing links, they are added
during the configuration.
Change test
Add a test to avoid warnings in log
Change test on URL parameter
Merge branch 'share' of https://github.com/aledeg/FreshRSS into share

Conflicts:
	app/Models/Configuration.php
Merge pull request #447 from aledeg/share

Sharing optimization