Check if the output supports colors (fixes #244)

This avoids using colors when the output is, e.g., redirected to a
file. This requried a change to avoid passing the `--colour` flag to
shake (so that hadrian is in charge of colors).

Finally, I've changed the color for `putBuild` - using white
foreground color is problematic (this was not a problem before due to
passing the `--color` flag to shake that was forcing different color).

Signed-off-by: Michal Terepeta <michal.terepeta@gmail.com>

build.cabal-new.sh

@@ -55,5 +55,4 @@ popd
 "$root/.shake/build"       \
     --lint                 \
     --directory "$root/.." \
-    --colour               \
     "$@"

build.cabal.sh

@@ -43,5 +43,4 @@ fi
 cabal run hadrian --               \
     --lint                         \
     --directory "$absoluteRoot/.." \
-    --colour                       \
     "$@"

build.sh

@@ -49,5 +49,4 @@ ghc                                      \
 "$root/hadrian"            \
     --lint                 \
     --directory "$root/.." \
-    --colour               \
     "$@"

build.stack.sh

@@ -36,5 +36,4 @@ stack build --no-library-profiling
 stack exec hadrian --              \
     --lint                         \
     --directory "$absoluteRoot/.." \
-    --colour                       \
     "$@"

src/Base.hs

@@ -96,18 +96,22 @@ infixr 6 -/-
 -- | A more colourful version of Shake's putNormal
 putColoured :: Color -> String -> Action ()
 putColoured colour msg = do
-    liftIO $ setSGR [SetColor Foreground Vivid colour]
+    liftIO $ set [SetColor Foreground Vivid colour]
     putNormal msg
-    liftIO $ setSGR []
+    liftIO $ set []
     liftIO $ hFlush stdout
+  where
+    set a = do
+      supported <- hSupportsANSI stdout
+      when supported $ setSGR a
 
 -- | Make oracle output more distinguishable
 putOracle :: String -> Action ()
 putOracle = putColoured Blue
 
 -- | Make build output more distinguishable
 putBuild :: String -> Action ()
-putBuild = putColoured White
+putBuild = putColoured Blue
 
 -- | A more colourful version of success message
 putSuccess :: String -> Action ()