Add optional 'count' parameter for photos.getRandomPhoto (#39)

* I added the missing optional parameter count for unsplash.photos.getRandomPhoto()

* I improved the function unsplash.photos.getRandomPhoto()

README.md

@@ -421,8 +421,14 @@ unsplash.photos.getPhotoStats("mtNweauBsMQ")
 ### photos.getRandomPhoto({ width, height, query, username, featured, category })
 Retrieve a single random photo, given optional filters.
 
+The category parameter is deprecated and should not be used.
+
+When using this function, It is recommended to double check the types of the parameters,
+in particular for the parameters of type Array<number>.
+
 __Arguments__
 
+Argument 1:
 _An Object containing the follow keys:_
 
 | Argument | Type | Opt/Required |
@@ -432,7 +438,9 @@ _An Object containing the follow keys:_
 |__`query`__|_string_|Optional|
 |__`username`__|_string_|Optional|
 |__`featured`__|_boolean_|Optional|
-|__`category`__|_Array<number>_|Optional|
+|__`category`__ *(deprecated)*|_Array<number>_|Optional|
+|__`collections`__|_Array<number>_|Optional|
+|__`count`__|_string_|Optional|
 
 __Example__
 ```js
@@ -441,7 +449,9 @@ unsplash.photos.getRandomPhoto({ username: "naoufal" })
   .then(json => {
     // Your code
   });
+
 ```
+
 ---
 
 ### photos.uploadPhoto(photo)

src/methods/photos.js

@@ -76,18 +76,20 @@ export default function photos(): Object {
 
     getRandomPhoto: (options = {}) => {
       const url = "/photos/random";
+      const category = options.category || [];
       const collections = options.collections || [];
 
       const query = {
-        category: options.category,
         featured: options.featured,
         username: options.username,
         orientation: options.orientation,
+        category: category.join(),
         collections: collections.join(),
         query: options.query,
         w: options.width,
         h: options.height,
-        c: options.cacheBuster || new Date().getTime() // Avoid ajax response caching
+        c: options.cacheBuster || new Date().getTime(), // Avoid ajax response caching
+        count: options.count
       };
 
       Object.keys(query).forEach(key => {