Namespaceify Core

[clphillips]

Add namespace support for core.

Increase PHP requirement to 5.3+

https://github.com/Feathur/minphp/commit/d3af4d3c698bd7dc80432ec6129cf06980ae45bd

[clphillips]

Thanks @Feathur. Unfortunately I won't be able to use the contribution for a few reasons:

1. Namespace integration has already begun on the 1.0 branch (see 33aaa39).
2. For 1.0 the framework is being decomposed into independent libraries, and bridged over for backwards compatibility with version 0.x.
3. One issue you may wish to correct in your commit, is the use of multiple root namespaces. For example, you put Model in Lib\Model. A better choice might be Minphp\Lib\Model (essentially everything in minphp should live behind Minphp\). As I said the framework is being decomposed, so Model will end up in Minphp\Mvc\Model -- part of a totally independent library.

That's perfectly fine. My partner asked that we make the offer, but we had no expectation that you'd want to use it.