Upgrade minsdk to 21 (#378)

* Upgrade minSdk

* Add changelog entry about the upgrade

* Remove obsolete version checks

app/src/main/java/apps/amine/bou/readerforselfoss/AddSourceActivity.kt

@@ -2,7 +2,6 @@ package apps.amine.bou.readerforselfoss
 
 import android.content.Context
 import android.content.Intent
-import android.os.Build
 import android.os.Bundle
 import androidx.preference.PreferenceManager
 import androidx.constraintlayout.widget.ConstraintLayout
@@ -50,38 +49,24 @@ class AddSourceActivity : AppCompatActivity() {
 
         val scoop = Scoop.getInstance()
         scoop.bind(this, Toppings.PRIMARY.value, binding.toolbar)
-        if  (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
-            scoop.bindStatusBar(this, Toppings.PRIMARY_DARK.value)
-        }
+        scoop.bindStatusBar(this, Toppings.PRIMARY_DARK.value)
 
         val drawable = binding.nameInput.background
         drawable.setColorFilter(appColors.colorAccent, PorterDuff.Mode.SRC_ATOP)
 
 
         // TODO: clean
-        if(Build.VERSION.SDK_INT > 16) {
-            binding.nameInput.background = drawable
-        } else{
-            binding.nameInput.setBackgroundDrawable(drawable)
-        }
+        binding.nameInput.background = drawable
 
         val drawable1 = binding.sourceUri.background
         drawable1.setColorFilter(appColors.colorAccent, PorterDuff.Mode.SRC_ATOP)
 
-        if(Build.VERSION.SDK_INT > 16) {
-            binding.sourceUri.background = drawable1
-        } else{
-            binding.sourceUri.setBackgroundDrawable(drawable1)
-        }
+        binding.sourceUri.background = drawable1
 
         val drawable2 = binding.tags.background
         drawable2.setColorFilter(appColors.colorAccent, PorterDuff.Mode.SRC_ATOP)
 
-        if(Build.VERSION.SDK_INT > 16) {
-            binding.tags.background = drawable2
-        } else{
-            binding.tags.setBackgroundDrawable(drawable2)
-        }
+        binding.tags.background = drawable2
 
         setSupportActionBar(binding.toolbar)
         supportActionBar?.setDisplayHomeAsUpEnabled(true)