Verify Cabal functionality for various installs

This patch adds functionality to

* Test cabal build and cabal run in the CI workflow
* Test GHC 7.10.3 on Linux and ensures that it works
* On Linux, try hvr's PPA before ghcup

__tests__/project/Main.hs

@@ -0,0 +1,4 @@
+module Main where
+
+main :: IO ()
+main = putStrLn "Hello, Haskell!"

__tests__/project/Setup.hs

@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain

__tests__/project/project.cabal

@@ -0,0 +1,9 @@
+cabal-version:       >=1.10
+name:                project
+version:             0.1.0.0
+build-type:          Simple
+
+executable project
+  main-is:             Main.hs
+  build-depends:       base
+  default-language:    Haskell2010