bump version 0.8.3

Merge pull request #18 from HatsuneMiku3939/feature/filter-basic-auth…

…-password

filter basic auth password

Merge pull request #16 from HatsuneMiku3939/feature/add-support-self-…

…signed-cert

add suport self-signed cert related options

add suport self-signed cert related options

Merge pull request #13 from HatsuneMiku3939/feature/add-user-agent-op…

…tion

add user agent option

Merge pull request #12 from HatsuneMiku3939/fix/remove-contents-type-…

…warning

remove content-type warning

bump verion 0.6.0

Merge pull request #10 from HatsuneMiku3939/feature/header-support

request/response header support

dump version 0.4.0

remove gem build warning