Support custom charset

[valery1707]

Currently for all parts used harcoded charset UTF-8, but sometimes I want to use another charset.

[dmarkov]

@yegor256 please pay attention to this issue (par.21)

[yegor256]

@valery1707 would you be interested in contributing with a pull request?

[valery1707]

@yegor256 yes

[yegor256]

@valery1707 thanks, looking forward to it

[valery1707]

@yegor256, here it is: #53

[0crat]

@rultor please, ask @valery1707 to close this issue and read more

[0crat]

@yegor256 please, pay attention to this issue

[rultor]

@rultor please, ask @valery1707 to close this issue and [read more](http://www.yegor256.com/2014/...

@0crat Thanks for your request. @yegor256 Please confirm this.

[yegor256]

@rultor release, tag is 1.9

[rultor]

@rultor release, tag is 1.9

@yegor256 OK, I will release it now. Please check the progress here

[rultor]

@rultor release, tag is 1.9

@yegor256 Done! FYI, the full log is here (took me 16min)

[yegor256]

@valery1707 I believe version 1.9 includes the feature you were looking for. Many thanks for your contribution!

[0crat]

Oops! Job gh:jcabi/jcabi-email#51 was not in scope