Small CI improvements (#10699)

* [appveyor] Cache all the downloaded binaries

* [travis] Enable fast_finish

.travis.yml

@@ -4,6 +4,8 @@ language: c
 dist: xenial
 
 matrix:
+  fast_finish: true
+
   include:
     - os: linux
       env: NIM_COMPILE_TO_CPP=false

appveyor.yml

@@ -1,10 +1,5 @@
 version: '{build}'
 
-cache:
-- x86_64-4.9.2-release-win32-seh-rt_v4-rev4.7z
-- sqlite-dll-win64-x64-3160200.zip
-# - i686-4.9.2-release-win32-dwarf-rt_v4-rev4.7z
-
 environment:
   MINGW_DIR: mingw64
   MINGW_URL: https://sourceforge.net/projects/mingw-w64/files/Toolchains%20targetting%20Win64/Personal%20Builds/mingw-builds/4.9.2/threads-win32/seh/x86_64-4.9.2-release-win32-seh-rt_v4-rev4.7z/download
@@ -19,6 +14,11 @@ environment:
     - NIM_TEST_PACKAGES: true
     - NIM_TEST_PACKAGES: false
 
+cache:
+    - '%MINGW_ARCHIVE%'
+    - '%SQLITE_ARCHIVE%'
+    - '%OPENBLAS_ARCHIVE%'
+
 matrix:
   #allow_failures:
   #  - NIM_TEST_PACKAGES: true