Make the url database column a "text" type

[weotch]

I wanted to paste a long conditional twig statement in the URL like this (I added whitespace for readability):

{% if event.sender.site.handle == "prod" %}
    https://api.netlify.com/build_hooks/xxxxxx
{% elseif event.sender.site.handle == "en_CA" %}
    https://api.netlify.com/build_hooks/yyyyyy
{% elseif event.sender.site.handle == "fr_CA" %}
    https://api.netlify.com/build_hooks/zzzzzzz
{% endif %}

My use case is a webhook that triggers a different Netlify build hook depending on the Craft site. I have a different Netlify app for each Craft site.

I'm getting a SQL error of Data too long for column 'url' with this. I can workaround by marking multiple webhooks, but this would be cleaner IMO.

[weotch]

I created this PR for this change #60