Switch to flycheck (from flymake)

* Add to list of packages to install in pkg-init.el (flycheck is no
  longer required and goes away)
* Configure flycheck faces for warning, error etc.
* Enable for Python and PHP (untested but should work fine)
Clean up unused erlang config
Replace manually configured php-mode with elpa one

Only need this on rare occassions and don't need any specific
customization.
Update the solarized theme