Add license type UnspecifiedLicense.

Before this, AllrightsReservered had two separate meanings; the author
explicitly chose this license or not license was specified and therefore
defaults to AllRightsReserved.

The default license when no license is specified is now UnspecifiedLicense.

Closes: #2141
Merge pull request #2147 from erikd/master

Add license type UnspecifiedLicense.
Add Cabal and cabal-install version numbers when writing a new config file.

These values can be useful for debugging cabal issues.
Merge pull request #2152 from erikd/config

Add Cabal and cabal-install version numbers when writing a new config fi...
cabal-install/IndexUtils : Expose function getIndexFileAge.

* The function has type 'Repo -> IO Double'.
* It returns the age in days as a Double.
* Places that expected the age as an Int have been updated.
* Builds with ghc 7.4.2 and 7.8.3.
cabal-install/IndexUtils : Fix display of age now that its days as a Double.
Merge pull request #2150 from erikd/master

cabal-install/IndexUtils : Expose function getIndexFileAge.
Whitespace, 80-col violations.