支持使用Token方式访问K8S

[sampsonye]

Which changes (Bug/Feature):

Fixes #76

Special notes for reviewers:

1. 配置页面可以配置基于Service Account Token的K8S配置
2. 所有K8S配置均从数据库获取，本地文件获取配置方式废弃
3. 优化migration的初始化模式，由原来的从models.init初始化修改为从main中引入，migrations.init自行初始化

[codecov-commenter]

Codecov Report

Merging #107 (91ee038) into v1.5.0-feat-app-refactor (b6e82f2) will not change coverage.
The diff coverage is n/a.

@@                   Coverage Diff                    @@
##           v1.5.0-feat-app-refactor    #107   +/-   ##
========================================================
  Coverage                      4.67%   4.67%           
========================================================
  Files                            10      10           
  Lines                          1454    1454           
========================================================
  Hits                             68      68           
  Misses                         1384    1384           
  Partials                          2       2           

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[colynn]

/LGTM