feat: use cobra to provide subcommands, move sources to lib (#506)

- Use cobra in order to provide subcommands `serve` and `db`.
  - Subdir `cmd` is removed.
  - Subdir `cli` is created, which is a standard cobra structure.
- Sources related to the core are moved to subdir `lib`.
- #497 and #504 are merged.
- Deprecated flags are added. See https://github.com/filebrowser/filebrowser/pull/497#discussion_r209428120.
- [`viper.BindPFlags`](https://godoc.org/github.com/spf13/viper#BindPFlags) is used in order to reduce the verbosity in `serve.go`.


Former-commit-id: 4b37ad82e91e01f7718cd389469814674bdf7032 [formerly c84d7fcf9c362b2aa1f9e5b57196152f53835e61] [formerly 2fef43c0382f3cc7d13e0297ccb467e38fac6982 [formerly 69a3f853bd2821d2c52a435277aaac68a468d39b]]
Former-commit-id: 2f7dc1b8ee6735382cedae2053f40c546c21de45 [formerly b438417178b47ad5f7caf9cb728f4a5011a09f5e]
Former-commit-id: 07bc58ab2e1ab10c30be8d0a5e760288bfc4d4dc

build/build_all.sh

@@ -2,8 +2,8 @@
 
 cd $(dirname $0)/..
 
-if [ -d "rice-box.go" ]; then
-  rm -rf rice-box.go
+if [ -d lib/"rice-box.go" ]; then
+  rm -rf lib/rice-box.go
 fi
 
 if [ "$USE_DOCKER" != "" ]; then
@@ -41,9 +41,8 @@ if [ "$USE_DOCKER" != "" ]; then
     for d in "dist/" "node_modules/"; do
       docker cp filebrowser-tmp:/$WDIR/frontend/$d frontend
     done
-    for d in "vendor/" "rice-box.go" "filebrowser"; do
-      docker cp filebrowser-tmp:/$WDIR/$d ./
-    done
+    docker cp filebrowser-tmp:/$WDIR/cli/filebrowser ./filebrowser
+    docker cp filebrowser-tmp:/$WDIR/lib/rice-box.go ./lib/rice-box.go
   fi
   docker rm -f filebrowser-tmp
 else