parametrize sleep time and bump it to 600 milliseconds

The current value is too low and causes failures like this:
```
{ error: 4000000, message: 'Too many requests' }
```
According to Diawi support limit of status checks is two per second:

>Your guess is correct, there is a limit on the number of requests for the
>status check of an upload (2 requests every second)... >and it seems that
>the library your are using is making requests to fast.
>Could you try using 600ms instead of 300ms?

Signed-off-by: Jakub Sokołowski <jakub@status.im>

readme.md

@@ -44,6 +44,7 @@ const result = await upload({
     apiUploadEndpoint: 'rewriteDefauitDiawiUploadEndpoint',
     apiStatusEndpoint: 'rewriteDefauitDiawiStatusEndpoint',
     maxApiStatusCalls: 99,
+    sleepMilliseconds: 600,
     onUploadProgress: (progressPercent) => {
         console.log(`uploading: ${progressPercent}`);
     },

src/constants/index.ts

@@ -1,6 +1,7 @@
 export const API_UPLOAD = 'https://upload.diawi.com';
 export const API_STATUS = 'https://upload.diawi.com/status';
 export const DEFAULT_MAX_API_STATUS_CALLS = 30;
+export const DEFAULT_SLEEP_MILLISECONDS = 600;
 
 export enum JOB_STATUS {
     OK = 2000,

src/core/upload/index.ts

@@ -1,10 +1,11 @@
 import { ApiStatusResponse, ApiUploadProps, StatusOptions, UploadOptions } from '@app/types';
 import { rawUpload, fetchJobStatus } from '@app/core';
-import { JOB_STATUS, DEFAULT_MAX_API_STATUS_CALLS, API_UPLOAD, API_STATUS } from '@app/constants';
+import { JOB_STATUS, DEFAULT_MAX_API_STATUS_CALLS, DEFAULT_PROCEEDING_SLEEP_TIME, API_UPLOAD, API_STATUS } from '@app/constants';
 import { noop, sleep } from '@app/utils';
 
 interface Options extends UploadOptions, StatusOptions {
     maxApiStatusCalls?: number;
+    sleepMilliseconds?: number;
     onStatusProgress?: (status: JOB_STATUS) => any;
 }
 
@@ -15,6 +16,7 @@ export const upload = async (props: ApiUploadProps, options: Options = {}) => {
     // default params
     const {
         maxApiStatusCalls = DEFAULT_MAX_API_STATUS_CALLS,
+        sleepMilliseconds = DEFAULT_SLEEP_MILLISECONDS,
         onUploadProgress = noop,
         onStatusProgress = noop,
         apiUploadEndpoint = API_UPLOAD,
@@ -43,7 +45,7 @@ export const upload = async (props: ApiUploadProps, options: Options = {}) => {
                 throw new Error(message);
             }
             case JOB_STATUS.PROCEEDING: {
-                await sleep(300);
+                await sleep(sleepMilliseconds);
                 return checkStatus();
             }
             default: {