Added Transactions

...va/com/example/mobileapp/Recycler_View_Adapter_Group.java

.../example/mobileapp/Recycler_View_Adapter_Transaction.java

...ava/com/example/mobileapp/Recycler_View_Adapter_User.java

.../app/src/main/java/com/example/mobileapp/Single_Trip.java

...main/java/com/example/mobileapp/TransactionFragement.java

.../main/java/com/example/mobileapp/TransactionFragment.java

...main/java/com/example/mobileapp/Trip_Overview_Screen.java

Frontend/app/src/main/res/drawable-hdpi/get_symbol.png

Frontend/app/src/main/res/drawable-hdpi/splitter.png

Frontend/app/src/main/res/drawable-mdpi/get_symbol.png

Frontend/app/src/main/res/drawable-mdpi/splitter.png

.../app/src/main/res/drawable-v24/ic_launcher_foreground.xml

Frontend/app/src/main/res/drawable-xhdpi/get_symbol.png

Frontend/app/src/main/res/drawable-xhdpi/splitter.png

Frontend/app/src/main/res/drawable-xxhdpi/get_symbol.png

Frontend/app/src/main/res/drawable-xxhdpi/splitter.png

Frontend/app/src/main/res/drawable-xxxhdpi/get_symbol.png

Frontend/app/src/main/res/drawable-xxxhdpi/splitter.png

...tend/app/src/main/res/drawable/ic_launcher_background.xml

...pp/src/main/res/layout/fragment_transaction_fragement.xml