Epoch counting is one-off in multiple instances
🐛 Bug
Two issues occur:

The final epoch does not save a checkpoint during training.
Resuming from a checkpoint N will start the epochs at N+2.

Expected behavior

Final checkpoint should save a .ckpt file, as usual.
Should resume from epoch N+1.

Environment
* CUDA:
	- GPU:
		- Tesla V100-DGXS-16GB
		- Tesla V100-DGXS-16GB
		- Tesla V100-DGXS-16GB
		- Tesla V100-DGXS-16GB
	- available:         True
	- version:           10.1
* Packages:
	- numpy:             1.18.1
	- pyTorch_debug:     False
	- pyTorch_version:   1.6.0
	- pytorch-lightning: 0.9.0rc12
	- tensorboard:       2.2.1
	- tqdm:              4.46.1
* System:
	- OS:                Linux
	- architecture:
		- 64bit
		-
	- processor:         x86_64
	- python:            3.7.7
	- version:           #113-Ubuntu SMP Thu Jul 9 23:41:39 UTC 2020