Release 0.2.0

Major Features and Improvements

load method now supports new signal formats:
- DICOM
- EDF
- wav
meta component structure has changed - now it always contains a number of predefined keys.
Added channels processing methods:
- EcgBatch.keep_channels
- EcgBatch.drop_channels
- EcgBatch.rename_channels
Added apply_to_each_channel method.
Added standardize method.
Added complex ECG transformations:
- Fourier-based transformations:
  - EcgBatch.fft
  - EcgBatch.ifft
  - EcgBatch.rfft
  - EcgBatch.irfft
  - EcgBatch.spectrogram
- Wavelet-based transformations:
  - EcgBatch.dwt
  - EcgBatch.idwt
  - EcgBatch.wavedec
  - EcgBatch.waverec
  - EcgBatch.pdwt
  - EcgBatch.cwt

Changed signature of the following methods:
- EcgBatch.apply_transform
- EcgBatch.show_ecg
- EcgBatch.calc_ecg_parameters
Changed signature of the following pipelines:
- dirichlet_train_pipeline
- dirichlet_predict_pipeline
- hmm_preprocessing_pipeline
- hmm_train_pipeline
- hmm_predict_pipeline
wavelet_transform method has been deleted.
update method has been deleted.
replace_labels method has been renamed to rename_labels.
slice_signal method has been renamed to slice_signals.
ravel method has been renamed to unstack_signals.

Initial release of CardIO.