(add) pdf viewer via html
(fix) errors when excel table import
(fix) errors when excel table import
Merge remote-tracking branch 'origin/wed_for_pdf' into wed_for_pdf

Conflicts:
	app/src/main/assets/rating_table.xls
	app/src/main/java/com/mil/physicaltraining/Exercise/Exercise.java
	app/src/main/java/com/mil/physicaltraining/Workspace.java
Merge branch 'master' of github.com:imhatep/physical_training

Conflicts:
	app/src/main/AndroidManifest.xml
	app/src/main/java/com/mil/physicaltraining/ActionsActivity.java
	app/src/main/res/values/strings.xml