Combine and expand specs for feature query syntax

These were spread over a couple different places, and didn't cover
some error conditions.

Author: xzyfer

spec/libsass-closed-issues/issue_261/input.scss

@@ -0,0 +1,21 @@
+@supports (foo: bar) {
+   div {
+     foo: bar;
+   }
+ }
+ @supports not (foo: bar) {
+   div {
+     bar: baz;
+   }
+ }
+ @supports (foo: bar) and (bar: baz) {
+   div {
+     foo: bar;
+     bar: baz;
+   }
+ }
+ @supports (foo: bar) or (bar: baz) {
+   div {
+     bar: baz;
+   }
+ }

spec/libsass-closed-issues/issue_617/input.scss

@@ -0,0 +1,6 @@
+.foo {
+     display: block;
+     @supports (display: flex) {
+         display: flex;
+     }
+ }

spec/libsass-closed-issues/issue_261/expected_output.css renamed to spec/scss/feature-queries/basic/expected_output.css

@@ -0,0 +1,3 @@
+Error: Invalid CSS after "@supports ": expected @supports condition (e.g. (display: flexbox)), was "{"
+        on line 1 of /sass/spec/scss/feature-queries/without-query/input.scss
+  Use --trace for backtrace.

spec/scss/feature-queries/basic/input.scss

@@ -0,0 +1,4 @@
+Error: Expected "not".
+@supports {
+          ^
+  /sass/spec/scss/feature-queries/without-query/input.scss 1:11

spec/libsass-closed-issues/issue_617/expected_output.css renamed to spec/scss/feature-queries/nested/expected_output.css

@@ -0,0 +1,3 @@
+@supports {
+
+}