Escape special characters when saving recipe to database

[cydanil]

Description

This fixes #37, escaping special characters when saving recipes.
The content of a recipe is saved a html to preserve links and formatting. Special characters such as ampersand were not escaped and caused problems when deserializing (loading) the recipes.

How Has This Been Tested?

This was tested by creating a recipe with ampersands everywhere and formatting where applicable and seeing that the recipe is correctly displayed and exported (to PDF.)

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.