Added colorWithFullHex method and made colorWithHex deprecated.

Unfortunately `colorWithHex` returns bad colours for hexes beginning with zeros.

Example:
`UIColor *color1 = [AVHexColor colorWithHexString:@"#00545b"];` 
`//color1 == "UIDeviceRGBColorSpace 0 0.329412 0.356863 1"`

`UIColor *color2 = [AVHexColor colorWithHex:0x00545b];`
`//color2 == "UIDeviceRGBColorSpace 0.266667 0.333333 0.733333 0.333333"`

Reason:
There is now way to tell how many leading zeros we should pass to string in this step:
`NSString *hexString = [NSString stringWithFormat: @"%03X" , (unsigned int)hexadecimal];`

Solution:
I've made `colorWithHex` deprecated and created new method that needs full hex: `colorWithFullHex`.

Cheers!