Fixes travis builds on macOS

Changes:
1. Updates `.travis.yml` with proper versions of `gpg`
2. Updates `README.md` with minimal versions requirements

Cloeses #96

.travis.yml

@@ -40,7 +40,11 @@ matrix:
           packages:
           - shellcheck
     - os: osx
-      env: GITSECRET_DIST="brew"; GITSECRET_GPG_DEP="gnupg2"; SECRETS_GPG_COMMAND="gpg2"
+      env: GITSECRET_DIST="brew"; GITSECRET_GPG_DEP="gpg1"
+      sudo: false
+      language: generic
+    - os: osx
+      env: GITSECRET_DIST="brew"; GITSECRET_GPG_DEP="gnupg@2.0"
       sudo: false
       language: generic
 

README.md

@@ -4,14 +4,17 @@
 
 [![git-secret](https://raw.githubusercontent.com/sobolevn/git-secret/gh-pages/images/git-secret-big.png)](http://git-secret.io/)
 
+
 ## What is `git-secret`?
 
 `git-secret` is a bash tool to store your private data inside a git repo. How’s that? Basically, it just encrypts, using `gpg`, the tracked files with the public keys of all the users that you trust. So everyone of them can decrypt these files using only their personal secret key. Why deal with all this private-public keys stuff? Well, to make it easier for everyone to manage access rights. There are no passwords that change. When someone is out - just delete their public key, re-encrypt the files, and they won’t be able to decrypt secrets anymore.
 
+
 ## Preview
 
 [![git-secret terminal preview](https://asciinema.org/a/41811.png)](https://asciinema.org/a/41811?autoplay=1)
 
+
 ## Installation
 
 `git-secret` supports `brew`, just type: `brew install git-secret`
@@ -20,6 +23,15 @@ It also supports `apt` and `yum`. You can also use `make` if you want to.
 
 See the [installation section](http://git-secret.io/installation) for the details.
 
+### Requirements
+
+`git-secret` relies on several external packages:
+
+- `bash` since `3.2.57` (it is hard to tell the correct `patch` release)
+- `git` since `2.6`
+- `gpg` since `gnupg 1.4` to `gnupg 2.0`, versions `2.1` are not yet supported
+
+
 ## Contributing
 
 Do you want to help the project? Find an [issue](https://github.com/sobolevn/git-secret/issues) and send a PR. It is more than welcomed! See [CONTRIBUTING.md](CONTRIBUTING.md) on how to do that.
@@ -28,14 +40,17 @@ Do you want to help the project? Find an [issue](https://github.com/sobolevn/git
 
 If you found any security related issues, please do not enclose it in public. Send an email to `security@wemake.services`
 
+
 ## Changelog
 
 `git-secret` uses semver. See [CHANGELOG.md](CHANGELOG.md).
 
+
 ## License
 
 MIT. See [LICENSE.md](LICENSE.md) for details.
 
+
 ## Thanks
 
 Special thanks to [Elio Qoshi](https://elioqoshi.me/sq/) from [ura](http://ura.design/) for the awesome logo.