added new base attribute 'coordinates' to driver classes

[johntruckenbrodt]

This new attribute is required for all driver classes and is for example used by method geometry.
A new test ensures that this method can be called for the following cases:

• ASAR in ESA format (class ESA)
• ERS1 in ESA format (class ESA)
• ERS1 in CEOS format (class CEOS_ERS)
• PSR2 in CEOS format (class CEOS_PSR)
• S1 in SAFE format (class SAFE)

This required rewriting parts of the classes ESA and CEOS_ERS to remove calls to gdalinfo and instead directly read the metadata from the files. gdalinfo also reads the binary image data, which made it imposible to only add the metadata header/file to the repository for unit tests.
As a nice side effect, initializing a driver object is faster (although not as much as for SAFE data).