Added the PhoneNumber faker (#96)

* Added the documentation.

* Implemented the PhoneNumberFaker.

* Added the PhoneNumberFaker to the main faker classes.

README.md

@@ -27,6 +27,7 @@ A .NET port of the Ruby [faker](https://github.com/stympy/faker) gem
   - [Faker.Lorem](doc/lorem.md)
   - [Faker.Name](doc/name.md)
   - [Faker.Number](doc/number.md)
+  - [Faker.PhoneNumber](doc/phone_number.md)
   - [Faker.Pokemon](doc/pokemon.md)
   - [Faker.Random](doc/random.md)
   - [Faker.RickAndMorty](doc/rick_and_morty.md)

doc/phone_number.md

@@ -0,0 +1,42 @@
+# Faker.PhoneNumber
+
+Phone numbers may be in any of the following formats:
+
+  * 333-333-3333
+  * (333) 333-3333
+  * 1-333-333-3333
+  * 333.333.3333
+  * 333-333-3333
+  * 333-333-3333 x3333
+  * (333) 333-3333 x3333
+  * 1-333-333-3333 x3333
+  * 333.333.3333 x3333
+
+(Don't let the example output below fool you - any format can be returned at random.)
+
+```cs
+Faker.PhoneNumber.PhoneNumber() //=> "397.693.1309"
+
+Faker.PhoneNumber.CellPhone() //=> "(186)285-7925"
+
+// NOTE NOTE NOTE NOTE
+// For the 'US only' methods below, first you must do the following:
+Faker.Config.locale = 'en-US'
+// or for Canada
+Faker.Config.locale = 'en-CA'
+
+// US only
+Faker.PhoneNumber.AreaCode() //=> "201"
+
+// US only
+Faker.PhoneNumber.ExchangeCode() //=> "208"
+
+// Optional parameter: length=4
+Faker.PhoneNumber.SubscriberNumber() //=> "3873"
+
+Faker.PhoneNumber.SubscriberNumber(2) //=> "39"
+
+Faker.PhoneNumber.Extension() //=> "3764"
+
+Faker.PhoneNumber.Extension(2) //=> "36"
+```