Fix whitespace issues found by git diff --check, add gitattributes

Set per file type attributes in .gitattributes to fine-tune whitespace
checks.  With the associated cleanups, the tree is now clean for git

contrib/hstore/hstore--1.1--1.2.sql

@@ -5,7 +5,7 @@
 
 
 -- A version of 1.1 was shipped with these objects mistakenly in 9.3.0.
--- Therefore we only add them if we detect that they aren't already there and 
+-- Therefore we only add them if we detect that they aren't already there and
 -- dependent on the extension.
 
 DO LANGUAGE plpgsql
@@ -26,7 +26,7 @@ BEGIN
             AND  x.extname = 'hstore';
 
    IF NOT FOUND
-   THEN 
+   THEN
 
         CREATE FUNCTION hstore_to_json(hstore)
         RETURNS json

contrib/hstore/sql/hstore.sql

@@ -341,4 +341,3 @@ insert into test_json_agg values ('rec1','"a key" =>1, b => t, c => null, d=> 12
        ('rec2','"a key" =>2, b => f, c => "null", d=> -12345, e => 012345.6, f=> -1.234, g=> 0.345e-4');
 select json_agg(q) from test_json_agg q;
 select json_agg(q) from (select f1, hstore_to_json_loose(f2) as f2 from test_json_agg) q;
-