Add directory traversal mode

[VTimofeenko]

The script can have a new mode that allows posting a nested set of pages. Consider the following structure:

.
├── a
│   ├── a.confluencewiki
│   ├── attachment_1
│   └── b
│       └── b.confluencewiki
└── config.toml

2 directories, 4 files

Script would:

1. Create page "a", with content from 'a.confluencewiki'
2. Attach attachment_1 to "a"
3. Create child "b" of page "a" with content from b.confluencewiki

[VTimofeenko]

Add option to delete pages that do not correspond to existing files