Adding the maxVA and minVA methods to NumberUtils and test methods

Modifying the following methods from `NumberUtils` and `IEEE754rUtils` to implement with `varargs instead of regular `array`:
* `public static long max(final long... number)`
* `public static long max(final int... number)`
* `public static long max(final short... number)`
* `public static long max(final byte... number)`
* `public static long max(final double... number)`
* `public static long max(final float... number)`
* `public static long min(final long... number)`
* `public static long min(final int... number)`
* `public static long min(final short... number)`
* `public static long min(final byte... number)`
* `public static long min(final double... number)`
* `public static long min(final float... number)`

These methods were implemented with the parameter as a regular array and they are being modified in order to meet what was agreed at this mail stack http://markmail.org/message/cictjkzg3z2qkmda

For example 
```
NumberUtils.max(new int[] { 1, 2, 3, 4, 5, 6  }); // returns 6
IEEE754rUtils.max(new double[] { 1.2, 2.3, 3.5, 4.0, 5.1, 6.9  }); // returns 6.9
```
And since now the code below will also be possible
```
NumberUtils.max(1, 2, 3, 4, 5, 6); // returns 6
IEEE754rUtils.max(1.2, 2.3, 3.5, 4.0, 5.1, 6.9); // returns 6.9
```
Jira ticket https://issues.apache.org/jira/browse/LANG-1008