DotEnv replaced by Ixa/Wp-Config
Using dotEnv required manual setup whereas Ixa/Wp-Config integrates
with WordPress and Incenteev/ParameterHandler, which means
an easier installation on any environment.
.gitignore updated and .htaccess added in config/ folder
README.md updated to show new installation method
'feature/wp-config', Ixa Wp-Config added