Feature extra adapter methods

[ivacf]

Add extra methods to EasyAdapter and EasyRecyclerAdapter:

• getItems(): will return the underlying List of data items so provides more flexibility to interact with the Adapter.
• removeItem(T item): Removes a given item from the adapter and refreshes the AdapterView or RecyclerView
• removeItems(Collection items): Same as above but for a collection of items.
• addItems(Collection items): Add a collection of items and refreshes the AdapterView or RecyclerView
• setItemsWithoutNotifying(List): same as setItems(List) but this method does not call notifyDataSetChanged()

Also add unit tests for all the methods in EasyAdapter and EasyRecyclerAdapter.

[hitherejoe]

also the tests :(

[ivacf]

About the tests I'm giving up with travis. It seems to run out of memory while starting the emulator or something like that. I will change so it only runs the unit tests and not the functional tests that require the emulator. We can run the functional tests manually.

[ivacf]

There you go @hitherejoe, all green!. Ready for you to have a look again.