Paths in Kuttl TestSuite should be relative to the TestSuite File

Nobody has claimed this yet.

**What happened**:
I have a Kuttl Test Suite File:
```
apiVersion: kudo.dev/v1alpha1
kind: TestSuite
manifestDirs:
- ../manifests/
commands:
- command: ../bin/kubectl-kudo init
testDirs:
- ./common
```

This file is located in a folder structure:
```
.
├── bin
│   ├── kubectl-kudo_0.12.0
│   ├── kubectl_1.17.2
├── manifests
│   └── local-path-storage.yaml
└── suites
├── common
│   ├── install-test
│   │   ├── 00-assert.yaml
│   │   ├── 00-install.yaml
│   │   ├── params.yaml
│   │   └── params.yaml.template
│   └── kind-config.yaml
├── kuttl-common.yaml
```

When calling kuttl from a different directory, the manifests, binaries and testDirs are not found because they are looked up relative to the current working directory of the caller.

**What you expected to happen**:
Paths inside a TestSuite file should be relative to that file, not the current working directory of the caller.

**How to reproduce it (as minimally and precisely as possible)**:
Call kuttl with a TestSuite file from another directory.

**Environment**:
- KUTTL version (use `kubectl kuttl version`): 0.2.2

Start at the TestSuite file-loading and path-resolution entry point, then reproduce the reported invocation from a directory other than the suite's directory. Check how manifestDirs, commands, and testDirs are resolved; done means all three paths resolve relative to the TestSuite file rather than the caller's working directory.

Written by the indexing model from the issue text.