Bump PHP and MySQL required versions

[markjaquith]

We're bumping the minimum PHP version to 5.2.4, and are bumping the minimum MySQL version to 5.0. This is a ticket to track that.

To-do: update WP.org API to not offer WP >= 3.2 to anyone who doesn't meet the requirements.

[markjaquith]

(In [17523]) Bump PHP requirement to 5.2.4. Bump MySQL requirement to 5.0. see #16917

[nacin]

Replying to markjaquith:

To-do: update WP.org API to not offer WP >= 3.2 to anyone who doesn't meet the requirements.

The API returns 3.2, but it also returns the PHP version, which is handled in list_core_update(). However the API code wasn't written to handle WP version-specific PHP/MySQL requirements, which I'm working on now.

[hakre]

Duplicate: #16804

[dd32]

(In [17534]) Remove PHP4 based WP_Http_Fopen class. Props sivel for initial patch. See #16917 Fixes #13915

[hakre]

Related: #16920

[nacin]

Replying to markjaquith:

To-do: update WP.org API to not offer WP >= 3.2 to anyone who doesn't meet the requirements.

Done: ​http://api.wordpress.org/core/version-check/1.5/?version=3.2.

[duck_]

Readme "System Requirements" need bumping too.

[nacin]

(In [17562]) Bump readme system requirements. props duck_, see #16917.