Add validation for configuration parameters

[ackintosh]

closes https://github.com/ackintosh/ganesha/issues/58

[coveralls]

Coverage increased (+0.4%) to 90.852% when pulling d98fce5c3e957e9dcf63da2c8fc3d9eb5532f73b on better-validation into 55860c967152a9d9a992280a9ede10fecf3432d2 on master.

[ackintosh]

📝

Switch how to pass build parameters from assosiated array to builder methods.

• users can find what parameters available easily via IDE's auto-completion functionality
• we can have benefits of the type hinting

$ganesha = Ackintosh\Ganesha\Builder::withRateStrategy()
    // The interval in time (seconds) that evaluate the thresholds. 
    ->timeWindow(30)
    // The failure rate threshold in percentage that changes CircuitBreaker's state to `OPEN`.
    ->failureRateThreshold(90)
    // The minimum number of requests to detect failures.
    // Even if `failureRateThreshold` exceeds the threshold,
    // CircuitBreaker remains in `CLOSED` if `minimumRequests` is below this threshold.
    ->minimumRequests(10)
    // The interval (seconds) to change CircuitBreaker's state from `OPEN` to `HALF_OPEN`.
    ->intervalToHalfOpen(5)
    // The storage adapter instance to store various statistics to detect failures.
    ->adapter(new Ackintosh\Ganesha\Storage\Adapter\Memcached($memcached))
    ->build();

$ganesha = Ackintosh\Ganesha\Builder::withCountStrategy()
    // The failure count threshold that changes CircuitBreaker's state to `OPEN`.
    // The count will be increased if `$ganesha->failure()` is called,
    // or will be decreased if `$ganesha->success()` is called.
    ->failureCountThreshold(100)
    // The interval (seconds) to change CircuitBreaker's state from `OPEN` to `HALF_OPEN`.
    ->intervalToHalfOpen(5)
    // The storage adapter instance to store various statistics to detect failures.
    ->adapter(new Ackintosh\Ganesha\Storage\Adapter\Memcached($memcached))
    ->build();