Modify travis-ci, fix issues

Added:
* Release/Debug job for gcc 7 and clang 3.5
* Debug asan gcc 7 job
* Debug tsan gcc 7 job
* Disabled extensions
* Added a spdlog::spdlog alias for tests

Removed:
* Valgrind workaround, the current version is 3.10.1
* install_libcxx
* Makefiles

Fixed:
* examples build
* multisink build

Workarounds:
* gcc7 with tsan and asan needs gold linker, otherwise build
  fails becase of unrecognized option '--push-state'

tests/Makefile

@@ -1,22 +0,0 @@
-CXX	?= g++
-CXXFLAGS	=  -Wall  -pedantic -std=c++11 -pthread -O3 -I../include -fmax-errors=1
-LDPFALGS = -pthread
-
-CPP_FILES := $(wildcard *.cpp)
-OBJ_FILES := $(addprefix ./,$(notdir $(CPP_FILES:.cpp=.o)))
-
-    
-tests: $(OBJ_FILES)    
-	$(CXX) $(CXXFLAGS) $(LDPFALGS) -o $@ $^
-	mkdir -p logs
-
-%.o: %.cpp
-	$(CXX) $(CXXFLAGS) -c -o $@ $<
-
-clean:
-	rm -f tests *.o logs/*.txt     
- 
-rebuild: clean tests
-
-
-