Added symlink to install step.

singularity/Makefile

 VERSION := $(shell git log | head -1 | cut -d " " -f2)
 
 ifeq ($(PREFIX),)
-	PREFIX := /opt/bioinfo_utils_$(VERSION)
+	PREFIX := /opt/bioinfo_utils
 endif
 
 
 install: all
-	install -d $(PREFIX)/bin
-	install run_pipeline $(PREFIX)/bin/.
-	install run_pipeline.sh $(PREFIX)/bin/.
+	install -d $(PREFIX)_$(VERSION)/bin
+	install run_pipeline $(PREFIX)_$(VERSION)/bin/.
+	install run_pipeline.sh $(PREFIX)_$(VERSION)/bin/.
 	for datatype in sRNA-seq smallRNA-seq RNA-seq GRO-seq PRO-seq Degradome-seq Ribo-seq iCLIP-seq iCLIP; \
 	do \
-	    ln -s $(PREFIX)/bin/run_pipeline.sh $(PREFIX)/bin/run_$${datatype}_pipeline; \
+	    ln -sf $(PREFIX)_$(VERSION)/bin/run_pipeline.sh $(PREFIX)_$(VERSION)/bin/run_$${datatype}_pipeline; \
 	done
+	ln -sf $(PREFIX)_$(VERSION) $(PREFIX)
 
 all: run_pipeline