Match DBus Trigger with phosphor-dbus-interfaces

Matched Trigger DBus interface to the one defined in
phosphor-dbus-interfaces repository. Changed enum (int) type to
string to reflect enum type defined in Trigger.yaml.
Fixed style in boost_build_1.74.0.sh script.

Tested:
 - Passed unit tests
 - Verified manually Trigger DBus object in witherspoon image
   on QEMU

Change-Id: I87175fc285afd182d1383da5879f89233b9de6a0
Signed-off-by: Wludzik, Jozef <jozef.wludzik@intel.com>
diff --git a/scripts/boost_build_1.74.0.sh b/scripts/boost_build_1.74.0.sh
index 074e72c..2775b7c 100755
--- a/scripts/boost_build_1.74.0.sh
+++ b/scripts/boost_build_1.74.0.sh
@@ -13,5 +13,5 @@
     ./b2 install --prefix=build
 fi
 
-echo -e "Please, set BOOST_ROOT to `pwd`/build, e.g.:\n" \
-        "export BOOST_ROOT=`pwd`/build"
+echo -e "Please, set BOOST_ROOT to $(pwd)/build, e.g.:\n" \
+        "export BOOST_ROOT=$(pwd)/build"