+ added a simple "length_validator"

this will validate phone numbers which country have fixed length numbers
+ updated some countries with length validator
+ documentation for length_validator
+ lenght validator now can take a hash for different ndc lengths

Example:

validate_lengths({ 2 => 6, 3 => 7, 4 => [8,9] })

phone numbers with a two digit ndc are 6 digits long, numbers with a 3 digit
ndc are 7 digits long, 4 digit ndcs can be 8 or 9 digits long
+ added a bit more documentation
+ added HongKong
+ added Haiti & Iran
+ added Seychelles, Sri Lanka
+ added India
+ length validation for 255
+ implement new syntax for length validation
+ fix problem with malaysian mobile numbers

that leads to a problem with malaysian service numbers, so I have commented
them out for now
+ update formatting of NL numbers
+ length validation for Nigerian numbers
+ changed formatting of morrocan mobile numbers
+ changed italy mobile ndc to 3 digits
+ Length validations for Germany and Italy
+ Updated Argentina, added El Salvador
+ updated README
+ change length validation for german 3 digit ndcs to be more strict

this could lead to valid german landline numbers not being considered valid.
However, for our use case, we are only interested in mobile numbers...