Change the version numbers to x.x.x.x format for linux and OSX

Earlier I made changes for windows to follow the 'major.minor.build.revision' model for versioning.
This format is enforced by MSI authoring tools. It makes sense to follow the same format for Linux and OSX too, now we have uniform version numbers for all platforms.

build.sh

@@ -40,12 +40,13 @@ export PATH=$DOTNET_INSTALL_DIR/bin:$PATH
 
 # UTC Timestamp of the last commit is used as the build number. This is for easy synchronization of build number between Windows, OSX and Linux builds.
 LAST_COMMIT_TIMESTAMP=$(git log -1 --format=%ct)
+major=1
+minor=0
+# no. of days since epoch
+build=$(($LAST_COMMIT_TIMESTAMP/3600/24))
+revision=$LAST_COMMIT_TIMESTAMP
 
-if [ "$(uname)" == "Darwin" ]; then
-    export DOTNET_BUILD_VERSION=0.0.1-alpha-$(date -ur $LAST_COMMIT_TIMESTAMP "+%Y%m%d-%H%M%S")
-else
-    export DOTNET_BUILD_VERSION=0.0.1-alpha-$(date -ud @$LAST_COMMIT_TIMESTAMP "+%Y%m%d-%H%M%S")
-fi
+export DOTNET_BUILD_VERSION=$major.$minor.$build.$revision
 
 header "Building dotnet tools version $DOTNET_BUILD_VERSION - $CONFIGURATION"