chore: optimize Makefile

docs: update README.md and CHANGELOG.md

perf(fetch): increase files transfer efficiency (#33)

perf(push): increase files transfer efficiency (#32)

refactor: optimize flags

Flag `-i,--auth.identity-files` changed to `-I,--auth.identity-files`,
and flag `-H,--hosts.inventory` changed to `-i,--hosts.inventory`.

docs: update CHANGELOG.md and README.md

refactor: optimize subcommand 'config'

chore: update CHANGELOG.md and README.md

feat: add support for hosts grouping (#29)

Support group hosts, group vars and group combination in inventory file.

E.g:

```text
node1.sre.im

[webserver]
node2.sre.im port=1001
node3.sre.im

[webserver:vars]
port=2002
user=zhangsan

[dbserver]
db[1-3].sre.im

[project1:children]
webserver
dbserver
```

Fixes #29
Fixes #27

feat: 🍻add variables to host file (#27)

Allow adding variables to inventory(host file), available variables:

```text
host
port
user
password
keys
passphrase
```

Example host file:

```text
alias_name_node1 host=node1.sre.im
alias_name_node2 host=192.168.33.12 port=22 user=vagrant password=vagrant keys=~/.ssh/id_dsa,~/.ssh/id_rsa passphrase=xxx
node3.sre.im user=vagrant password=GOSSH-AES256:9cfe499133b69a6c7fc62b5b6ba72d3d8dfb4d0e7987170a40c5d50bb5d71e19
```