Various minor changes on optee examples

Prefix test applications for the examples with 'optee_example_'.
Gitignore the generate test applications.
Few extra minor changes as make verbosity and source coding style.
STR_TRACE_USER_TA is deprecated.
Update README.

Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Joakim Bech <joakim.bech@linaro.org>
diff --git a/random/host/Makefile b/random/host/Makefile
index fcd05f2..8d063ae 100644
--- a/random/host/Makefile
+++ b/random/host/Makefile
@@ -8,11 +8,11 @@
 
 OBJS = main.o
 
-CFLAGS += -Wall -I../ta/include -I$(TEEC_EXPORT)/include -I./include
-#Add/link other required libraries here
+CFLAGS += -Wall -I../ta/include -I./include
+CFLAGS += -I$(TEEC_EXPORT)/include
 LDADD += -lteec -L$(TEEC_EXPORT)/lib
 
-BINARY = optee_random
+BINARY = optee_example_random
 
 .PHONY: all
 all: $(BINARY)