Remove UA_BUILD_DOCUMENTATION switch

It is not used anymore, since doc and doc_pdf targets are created automatically

tools/travis/travis_linux_script.sh

@@ -58,7 +58,7 @@ else
     echo -e "\r\n== Documentation and certificate build =="  && echo -en 'travis_fold:start:script.build.doc\\r'
     mkdir -p build
     cd build
-    cmake -DCMAKE_BUILD_TYPE=Release -DUA_BUILD_EXAMPLES=ON -DUA_BUILD_DOCUMENTATION=ON -DUA_BUILD_SELFSIGNED_CERTIFICATE=ON ..
+    cmake -DCMAKE_BUILD_TYPE=Release -DUA_BUILD_EXAMPLES=ON -DUA_BUILD_SELFSIGNED_CERTIFICATE=ON ..
     make doc
     make doc_pdf
     make selfsigned

tools/travis/travis_osx_script.sh

@@ -12,7 +12,7 @@ else
 
     echo "Documentation and certificate build"  && echo -en 'travis_fold:start:script.build.doc\\r'
     mkdir -p build && cd build
-    cmake -DCMAKE_BUILD_TYPE=Release -DUA_BUILD_EXAMPLES=ON -DUA_BUILD_DOCUMENTATION=ON -DUA_BUILD_SELFSIGNED_CERTIFICATE=ON ..
+    cmake -DCMAKE_BUILD_TYPE=Release -DUA_BUILD_EXAMPLES=ON -DUA_BUILD_SELFSIGNED_CERTIFICATE=ON ..
     make selfsigned
     ls examples
     cp examples/server_cert.der ../