[ANN] rasn1 0.7.1 released

rasn1 0.7.1 has been released.

* home: <https://github.com/sdaubert/rasn1>
* bugs: <https://github.com/sdaubert/rasn1/issues>
* doc: <https://github.com/sdaubert/rasn1/wiki>

RASN1 is a pure ruby ASN.1 library. RASN1 helps to create ASN.1 parsers
and encoders.

Changes:

### 0.7.1 / 2019-11-11

* Add support for bundler 2.0

### 0.7.0 / 2019-11-11

* add RASN1::Model#value to get value of a (potentially nested) element.
* add RASN1::Types::Sequence#[]. Access to element by index or by name.
* add frozen_string literal.
* fixed bug:
  * RASN1::Types::Base#initialize_copy raises on ruby 2.3 when @value
and/or @default were nil, true, false of Integer.