Allow video with no audio stream present to be transcoded

[coryjthompson]

Related to #23.

[juliooa]

@ypresto Can you approve/merge this?
It will be very useful to allow transcoding videos without audio, right now it throws an exception.

[tobias-r]

When will this be released? It doesn't work with 0.3.0?

Btw, is there a way to add an implementation in Android Studio Gradle for this exact comment supporting videos without audio? Tried to find a way, but found nothing.

[tobias-r]

Again, please release this version, today many people do drone videos or time lapse without audio.

[AlexTrotsenko]

In case somebody need to have this change right now (until author will merge it):

You can get it via JitPack:

1. Add JitPack as repo:

	allprojects {
		repositories {
			...
			maven { url 'https://jitpack.io' }
		}
	}

2. And add dependency

	dependencies {
	        implementation 'com.github.AlexTrotsenko:android-transcoder:aa7dc58615'
	}

In more details:

• I have merged master of this repo (which is not released, btw) and this PR:
  https://github.com/AlexTrotsenko/android-transcoder/commits/2020_04_noaudiostreamfix
• Use JitPack to build and deliver result of my merge.
• I have also send MR to the author of original MR to be up-to-date with current master:
  Merge with latest master (as of 07.04.2020)  coryjthompson/android-transcoder#1

[rahulapatil]

The code for transcoding video with no audio is not working. Please look into it.